hMailServer

It has most of the functions necessary for a mail server, sufficient both for a local test mailer and for solving the problems of small companies.

Here are just some of its features (taken from the project website):

Main features POP3, SMTP, IMAP Virtual domains Built-in backup SSL encryption Anti-spam Anti-virus Scripting Server-side rules

Multilingual Routing MX backup Multihoming SQL backend Web administration Integrations ClamWin SpamAssassin

The program consists of two parts - a service that performs all functions for working with mail, and graphical shell administrator, which allows you to manage not only local but also remote servers. To store your settings and indexes that speed up work with big amount letters, a database is used. MS SQL Server Compact is installed by default, but PostgreSQL, MySQL, MS SQL are also supported.

One of the most interesting features This program, in my opinion, is supported by VB scripts, which expands the capabilities of mail processing and allows you to customize the program to specific needs. For example, you can write a script that will distribute all incoming letters from one mailbox to two others alternately , that is, even letters go to one, odd letters to the other. The site has a whole forum section dedicated to scripts with examples of their implementation.

Also included is an administrator web interface written in PHP, which can be connected to an existing website on Apache or IIS.

Mercury Mail Transport System (Mercury/32)

Website: http://www.pmail.com/index.htm


Mercury Mail Transport System is included with XAMPP (http://ru.wikipedia.org/wiki/XAMPP - a cross-platform web server assembly containing Apache, MySQL, PHP script interpreter, Perl programming language and a large number of additional libraries that allow you to run a full-fledged web server.)
Has quite wide possibilities, however, although it is positioned as free, for full use as a mail server (running as a service) and use for commercial purposes, it requires a paid license.

Supported protocols:

Protocols supported

• - To run as a service, a commercial license is required.

Let's start with what I mean by medium-sized business. I don’t know the exact classification and I haven’t looked or checked anywhere. It intuitively seems to me that this is from 10-15 users to 200-300. I will consider the segment up to 100 users, since I work exclusively in this niche almost all the time. The problems and needs of larger companies are not reliably known to me. Although I’m not sure that anything will be fundamentally different from 100 people, I think the approaches will be the same, only the hardware will be more powerful. The problems of load distribution and clustering will most likely not arise here yet.

We have a small company of several dozen people. We need a mail server. Despite the fact that technology has long stepped forward, providing a lot of various means of communication, e-mail still firmly holds its position and is not going to give it up yet. At the same time, in such a small team, there are no great demands on the mail server. Most often, it is enough for the mail to simply work, without any special functional frills. Either an email client and the imap protocol, or a web interface will be sufficient. It would be good if it were possible to set up an auto-reply, create shared folders, a single address book, but you can live without it.

Among all possible options mail service, I identify 3 fundamentally different approaches to implementing the necessary functionality:

1. Services based on free email services from Google, Yandex or mail.
2. Your own mail server based on free software.
3. Exchange server from Microsoft.

Let's look at each of them in more detail.

Free mail from google, yandex and mail.ru

I'll make a couple of comments right away. I'm not sure if you can register with Google for free now corporate mail. Everyone who registered earlier uses it for free, and for new users only paid subscriptions. But this is not important and does not directly relate to the topic of the article. If Google has become completely paid for business, then we’ll simply exclude it from our list. Yandex and Mail.ru are still definitely free. I myself administered email domains in Google apps and Yandex. I haven’t worked with biz.mail.ru, I just know that something similar is implemented there. Somehow I don’t like the company itself since the old days. Although now they seem to have turned to face the users, Amigo is still alive and well, so they have not completely turned around yet.

Let's look at the advantages of these email services.

1. The most important advantage is that full-fledged mail is ready immediately after registration. There are no costs for purchasing hardware and setting up. It is enough for a more or less advanced user who, according to the instructions on the site, can connect a domain and create mailboxes. And you can already use mail.
2. Easy to administer and manage users, the web service provides all the necessary equipment for this. They are convenient and intuitive (though not always) understandable.
3. Comfortable and familiar web interface. Everything works quickly, from any place where there is Internet and a browser. There is a good mobile application.
4. Wide functionality, ready immediately after creating the box. Various filters, mail collectors, good antispam (from Google) and much more.

It seems like everything, I didn’t miss anything. It would seem that the advantages are obvious and significant. But before drawing conclusions, let's consider the disadvantages.

1. You do not manage this mail. She doesn't belong to you, is not on your servers. You don't know what's happening to her. If you have very sensitive and private correspondence, then suspicions and doubts arise about using popular email services. This may sound like paranoia, but this is a real concern for users and business owners and should not be discounted.
2. You are not immune from system failures and cannot prevent them in any way. And failures, although not often, do occur. Since the services are free, no one will guarantee you anything. And if some force majeure happens and the data is lost, they will simply say sorry to you. If you yourself do not have a very reliable IT structure, the likelihood of technical problems on your personal server may be higher. But you can control this and theoretically be able to build a system with a level of reliability that satisfies you.
3. Backup methods are not obvious and recovery of mailboxes in such services. There are situations when mailbox delete all letters. Let's say you can save them different ways, just downloaded, but how can you return it back to the box, keeping all the dates original?
4. There is no way to analyze incomprehensible situations. For example, you send a letter, but it does not reach the recipient. What to do? In the case of cloud mail, you will not do anything, since you do not have any tools to analyze the situation. Just try sending a letter from another mailbox. Sometimes a letter doesn’t arrive to you, and you just can’t understand why it’s not there. But the issue may simply be an incorrectly configured filter. This is a common situation when there are a lot of filters, plus if some other forwarding is configured. Without access to server logs, it can be difficult to understand the situation. And if there is a mail server log, then it immediately becomes clear why the letter is not sent, or what happened to it after receiving it. You can know for sure whether the remote server received your letter or not.
5. No simple ways restrict access to mailboxes, for example, only from local network office. Public service mailboxes are always accessible via the Internet. It is possible to solve this problem in google apps through authorization in third-party services. I have not seen the opportunity to implement such functionality in Yandex and mail.
6. We also need to understand that free cheese knows where it happens. It is not entirely clear how email services use the information received from users. Well, if only to show them relevant advertising. I think not only for this.

When I first started working about 10 years ago, there was no question about what email to use in the organization. Everyone set up their own mail servers and administrated them. At that time, free email services did not provide any email management tools for businesses. When such tools began to appear, I thought that soon no one would need their own mail servers, since they would no longer make sense. And all my torment (I don’t like working with them) with mail servers will become meaningless.

I was given the opportunity to administer domains based on public email services. After this, the above list of minuses appeared. And for me personally, these disadvantages outweighed the advantages, and now I still configure mail servers myself. Ultimately, it is more convenient and reliable when the pros and cons of use and administration are considered together.

The biggest disadvantage I see is the lack of full-fledged mail logs and a good backup scheme. It is inconvenient to analyze problems without logs. It is not possible to quickly and easily restore a deleted email to its original location, although this is a simple matter for open source mail servers.

Mail server based on free software

Let's look at the advantages and disadvantages of our own mail server based on the free software. In principle, this includes some paid ones, for example Kerio Mail Server, which is also often used. I think it can be included here, since it provides similar functionality. I consider all mail servers collectively, without singling out individual representatives. Although in Linux, besides postfix and exim, I personally have not seen anything in production. I always use postfix myself, because I’m used to it and know it well. Let's take a closer look at the advantages of such servers.

1. You are in complete control of all information, which arrives by mail and is stored on your server. You can limit access to mail by various means at your discretion. technical means. You can centrally set up rules for deleting, for example, private information in letters, based on various criteria that you can set yourself.
2. The level of availability of the mail service depends only on you. With the right approach, you can provide the reliability that suits you system operation.
3. Flexible backup system. There are plenty of resources for organizing it, including free ones. It all depends on your needs, skills and capabilities. You can store various sections by date, by box, domain, or organize any suitable scheme.
4. Virtually unlimited functionality. Within reasonable limits, of course :) You can create mailboxes with only local correspondence, you can centrally manage the reception and sending of mail, and maintain your own white and black lists. You can set up various restrictions on mailboxes and domains. You can easily centrally manage duplication of mail for the required mailboxes, make all kinds of forwarding and much more.
5. All server monitoring tools are in your hands. You can deal with any unclear situation, having the mail server logs in hand. This service is well logged. I almost never had problems when it was not clear where the letter went missing. Most often, traces are found and one can definitely say what happened to the letter.

1. Necessary buy or rent equipment to organize your own mail server. In the case of a Linux server, the performance requirements will not be great. A virtual machine with 4 cores and 4 GB is usually enough for me random access memory. The disk subsystem is much more important. Here, the faster the disks, the better. Don't forget about backup. It also requires iron resources.
2. Setting up a full-fledged, multifunctional mail server requires at least average knowledge of Linux system administration. That is, just admin username will not work here. Need a specialist with experience. He must have a decent salary. If such an admin is not on staff, I recommend hiring someone for one-time setup work. Most often, after setup, no special work is required to support the server if you do not change the functionality. It’s enough to simply monitor the free disk space and manage mailboxes via the web panel.
3. Ease of use via web interface will be lower than in free postal services. Whatever one may say, but the same gmail is implemented very conveniently. Quick search, filters, sorting, labels, etc. It's really convenient. I'm very used to it and can't use anything else.

These are the disadvantages of my email service that I see. The most important one for me is the last one. I myself am used to working with mail via the web. I don’t like to use email clients, although I have to. Web interface In terms of convenience and speed, free mail servers are far from being comparable to Gmail or Yandex; it makes no sense to compare. Nevertheless, I believe that for the average organization this is the most optimal option.

Pros and cons of Microsoft Exchange Server

I don't have much experience administering exchange. I tested it a long time ago when I was deciding which mail servers I would work with. I installed it and studied the functionality. Then I set up a mail server for the organization once. They wanted exchange. There were no problems, I quickly set it up using numerous guides on the Internet. The entry threshold for exchange mail server customizers is very low. Even Enike can handle basic functionality.

For medium-sized organizations, I think shared calendars are a really useful and difficult-to-replace functionality. And of course, the convenience of integration with AD, if available. And most often there is AD, since I can’t imagine administering a network for more than 20-30 people without Active Directory. I think that there is no point in saving here and you need to buy Microsoft Server.

Let's now look at the pros and cons of Microsoft Exchange Server. I warn you again just in case. I’m only telling you my vision, I have little experience working with the server, so I would like to receive comments on it myself in the comments in order to have a more adequate assessment of this system. Pros of Exchange:

1. Great functionality with relative ease of setup. Any administrator can deploy a server with basic functionality. Moreover, this basic functionality may be greater than that of any Linux build.
2. Active Directory Integration. You are creating a new one account user and his mailbox is immediately ready. No special settings are needed if the user has Microsoft Outlook. A connection to the server is configured in a few clicks of the mouse.
3. Comfortable administration tools in the form of ready-made equipment Windows Server. Everything here is traditional for solutions from Microsoft.

The disadvantages of Exchange Server are as typical as the advantages for most products from Microsoft:

1. Price, price and price again. Microsoft Exchange Server is expensive. You need to count and figure out whether it will be justified to purchase it. To use all the built-in functionality, you will need for each workplace buy edition Microsoft Office with Outlook included. These are additional costs.
2. For good performance it is required significantly more powerful iron, compared to Linux servers. And to support large mailboxes, for example 50 gigabytes, you will need very powerful hardware. Although such boxes do not represent dovecot special problems. In exchange, you will most likely use quotas to limit the maximum mailbox size.
3. For backup, you will most likely have to purchase decently powerful hardware and paid software. Here I’m just guessing, I really don’t know what is needed for a convenient exchange backup. I know paid software from popular vendors. Perhaps there is something free.

My conclusion about Exchange Server is that it is good in almost everything except the price. If it were free, I would most likely use it. For quite objective reasons, this is impossible. Good and convenient software does not appear on its own. You need to create it, and spend money on it, which you want to return with a profit.

Today, given the cost of Microsoft Exchange Server and Microsoft Office, I do not use these Microsoft products. Few people are willing to shell out the required amount for a mail server. I would like to take a closer look at Exchange in real conditions for at least 60-80 people in order to evaluate this server more objectively. But so far such an opportunity has not presented itself.

Conclusion

Let me summarize my thoughts about a mail server for a small, average organization. Although the conclusion, I think, is already clear. I myself prefer the second option I described - a mail server based on free software on Linux. But I wouldn’t discount the other two options. Free mail from public services will definitely be convenient for a very small team - 10-15 people. It makes no sense to fence your server for such a large number.

I would recommend using Exchange Server if you have it and don’t mind spending money on purchasing it. The product is definitely convenient, functional and easy to set up and administer. To put it simply, you need to understand that this is conditional. Configurations can be very complex, but in this case I am considering the entry level.

Online course "DevOps practices and tools"

If you have a desire to learn how to build and maintain highly available and reliable systems, learn continuous software delivery, monitoring and logging web applications, I recommend getting acquainted with online course “DevOps practices and tools” in OTUS. The course is not for beginners; to enroll you need basic knowledge of networks and installing Linux on a virtual machine. The training lasts 5 months, after which successful course graduates will be able to undergo interviews with partners. Test yourself on the entrance test and see the program for more details.

If you have a small office and it is too expensive for you to buy Exchange and you don't have *nix- then this review is for you.

1) hMailServer

A fairly simple and convenient server. Contains IMAP/POP3/SMTP server. There is a built-in anti-spam system. For those who like to view mail through Web- needs to be screwed separately Web-muzzle.

2) Mail Enable

Please note that there are paid and free versions of this product. Contains POP3/SMTP, but does not have IMAP server. But there is a built-in Web interface (which I never managed to get to work on IIS7)

3) XMail

A fairly simple and functional mail server ( POP3/ESMTP, but no IMAP) with support for several types of authorization ( PLAIN LOGIN CRAM-MD5 POP3-before-SMTP and custom)

4) Office Mail Server

There is no official website because the project is not developing. But you can download it from here http://www.box.com/oms

A simple, compact, but fully functional mail server for a local network with dial-up Internet connection. Works under Windows 95-98-NT-ME-2000. Can work like NT service. A powerful sorter allows you to provide each user on the local network with a personal email address. The program combines POP3 And SMTP servers, POP3 And SMTP clients, sorter, session scheduler, dialer and shell for configuring the server through a system of menus and dialogs.

5) chicks!

Simple POP3/SMTP server written in python

6) Courier Mail Server

Almost identical to Courier Mail Server 1.56 (completely free) - however, there are minor drawbacks. For example, a glitch with the display of the interface when working with the server through a terminal session. However, this does not affect the work of the post office. Its revised version 2.xx - www.courierms.ru Unfortunately, it is paid. It only works for free up to 3 mailboxes.

7) UserGate Mail Server

UserGate Mail Server is a solution for organizing secure email messages in a company with built-in antispam and antivirus protection. The product has a modular structure, which increases fault tolerance and makes it possible to run a server on a distributed system.
Among the main functions UserGate Mail Server- domain and user management, web client, mailing list support, working with remote accounts, support LDAP, as well as a flexible and powerful rules system. UserGate Mail Server capable of processing more 2000 letters per minute.
To provide access to mail in UserGate Mail Server protocol support implemented SSL, POP3s, SMTPs and IMAPs. The security of an email message can now be ensured by three anti-virus modules at once: Kaspersky Antivirus, Panda Antivirus And Entensys Zero-Hour based on cloud technologies.
In processing incoming messages in UserGate Mail Server Filtering is performed in several stages - by connection, by source address, by destination address and by content. UserGate Mail Server supports the following spam filtering methods:
based DNS (DNSBL, RHSBL, Backscatter, MX, SPF, SURBL);
based on a distributed antispam system (“cloud” antispam);
based on statistics (own implementation of Bayesian filtering).
Besides UserGate Mail Server maintains control SMTP protocol (monitoring the correctness of commands in accordance with RFC), limits maximum size letters, maximum amount recipients, etc.
Cloud antispam in the mail server filters out messages based on analysis of their content and heuristics.
IN UserGate Mail Server integration with IMAP– server MS Exchange or Lotus Domino. Integration provides the ability to create shared folder IMAP on a remote mail server and processing messages in these folders.
UserGate Mail Server provides information about all messages processed by the mail server. Message monitoring allows you to filter by date, by processing status (delivered/blocked), by source or destination address, force messages blocked as spam, and create exclusion lists.
Free license for 5 mailboxes
To be able to use UserGate Mail Server for 5 mailboxes for free, you must:
Download distribution; In the registration window UserGate Mail Server select "Get free version for 5 boxes."
Part free license mail server does not include additional modules.
UserGate Mail Server supports backing up email messages, sending automatic replies, setting up mail processing rules, managing services in the web console, and selecting a custom date range in the message history.

8) Rumble Mail Server

Rumble is a miniature email server for personal use. The application can only be launched from your system's command line interface.

Features of the Rumble program:
1. Support SMTP, POP3 and IMAP
2. Working with Apache
3.Easy to use
4. Rumble is free!

9) Humster

Hamster is a free server application for Windows that allows you to fully work with usenet news via the NNTP protocol and mail via the SMTP, POP3, IMAP protocols on a local network. Its feature is its advanced message processing capabilities. It can independently collect mail from mailboxes on the Internet (similar to the functioning of the fetchmail program in *nix), send it to a local mailbox, pre-processed (similar to the functioning of the procmail program in *nix), distribute via POP3, send via SMTP and NNTP. You can configure access rights to server resources for users. Rich macro language. SSL supported.

10) Axigen

Axigen mail server is a large-class communication server that integrates SMTP, POP3, IMAP and WebMail services. Having very good setup and security, gives administrators excellent control over mail server traffic.

hMailServer - free mail server under Windows platform. Distributed as open source. Works like Windows service and includes administration tools and Reserve copy. Supports IMAP, POP3 and SMTP mail protocols. The server has all the basic functions, such as support for multiple domains, aliases, mailing lists. User authorization can be carried out using the local hMailServer user database or through the Active Directory database.

hMailServer supports several different antispam mechanisms. It has built-in support for the ClamWin/ClamAV antivirus; the antivirus itself must be installed separately. It is possible to use any other antivirus scanner with command line. SpamAssassin can be used as an antispam filter. DNSBL - in stock.

For the web interface you can use SquirrelMail or RoundCube.

Can be used as a home mail server or as a small company mailer.

Possibilities

• Domain and account signatures.
• Server rules, rules for individual accounts.
• Receiving messages from external mail servers using the POP3 protocol.
• Quotas for domain, mailbox and mail messages.
• Creating virtual aliases for your account.
• Blocking attachments (depending on attachment file extension).
• Custom SMTP routes for selected domains (can be used for backups, redirects, etc.).
• Application programming interface (support for VBScript and JScript scripting languages).
• Built-in SSL support.
• Antivirus.
• Antispam.

I’ll tell you about the remaining features in a separate review. I have several years of operating experience of this server. I encountered only one bug - in the POP3 protocol, it was easily fixed using IMAP and disappeared after the next update. Updates are released rarely and are easy to install.

Links

Databases used

The email messages themselves are stored on your hard drive in MIME format. Uses databases to store settings and indexes:

• Microsoft SQL Server 2000 and later
• Microsoft SQL Server Compact Edition (CE)
• MySQL 4 and later
• PostgreSQL

Microsoft SQL Server Compact Edition (CE) is built into the installer, but there is a nuance:

Please Note: The bundled Microsoft SQL Server Compact Edition (MS SQL CE) is not supported by Microsoft for Windows 8, Windows 8.1, Windows 10, Server 2012, Server 2016. You will need to use an external database with these Operating Systems.

So use something else. I tried two database options: Microsoft SQL Server 2008 and MySQL 8.0. There were no problems with MSSQL. I had to fiddle with MySQL - I need to get a 32-bit library libmysql.dll, I didn’t immediately understand where to get it. I haven’t tried PostgreSQL, although this is recommended as the main option.

Installing a mail server

We will use the free mail server hMailServer as a mail server on Windows OS. We go to the Hmailserver website in the Download section and download the latest available version for installation. We start the server installation. At the installation type selection point, select complete. Select the type of database server; if you plan to have a large number of mailboxes and their safety is critical, select Use external database Engine (MSSQL, MySQL or PostgreSQL) Set the administrator password, be sure to remember it. After installation, a window for connecting to the server will appear. For ease of launching the application, set the option "Automatically connect on start-up" and click "Connect". On the welcome window, click the Add domain button... You can also add domains in the Domains-Add... section

Adding a domain

Select the domain and add a mail account in the Accounts section

These settings are already enough to use mail.

Description of hMailServer mail server settings

Status

In the Status-Server section we can see the current server status, look at the server version and the type of database server used. Configuration errors are also displayed there.

The Status-Status section contains server statistics, server uptime, number of emails processed, viruses and spam messages detected. This section also displays the number of active SMTP, POP3, IMAP sessions.

In the Status-Logging section, you can enable logging and monitor connections to the mail server live. In the Status-Delivery Queue section there is a mail queue, in the same section the mail queue can be cleared.

Domains

In the Domains section you can delete, add, edit domain settings. Let's take a closer look at domain settings.

In the General section you can enable/disable the mail domain. In the Names section you can add an alias for the mail domain. In the Signatures section, you can add a signature for letters sent from mailboxes of the specified mail domain. You can define the conditions for using a signature:

• For all mailboxes that do not have a signature
• Rewrite mailbox signature
• Add a signature to the mailbox signature

You can add a text and/or html signature.

In the Limits section, limits are set. Maximum Size (Mb) - sets a size limit for all mail messages in all mailboxes of the domain. Maximum message size (Kb) - if the value is specified, then hMailServer will reject messages larger than the specified value. If the parameter is not specified, the value specified in the SMTP settings will be used. Max size of accounts (Mb) - if the value is specified, the administrator will not be able to add accounts with a total volume exceeding the value. Also in this section you can configure the maximum number of accounts, aliases and mailing lists.

In the DKIM Signing section you can configure a DKIM signature. To generate a signature and key, I recommend using the dkim-wizzard resource. In the Pivate key file, we specify the file with the private key. In the Selector item, specify the selector that must match the DNS entry. For example, if your DNS record is named myselector._domainkey.example.net, you would enter "myselector" as the selector (without the quotes).

In the Advanced section, you can configure the address for forwarding mail that is sent to all non-existent mailboxes, enable the so-called “Plus addressing” and specify a symbol for it. You can enable/disable greylisting.

In the Domains-Accounts section, settings for each specific mailbox are made. The General tab contains the main account settings. Address, password and mailbox size. You can also specify the user's access level to the server:

• User - can change account settings, such as password.
• Domain - user can change basic settings domain and users in the domain. Can add users, aliases, mailing lists, delete objects, increase account limits.
• Server - the user can change the settings of the server and all domains in it.

On the Auto-reply tab, you can set up an auto-reply, specify the subject and message of the auto-reply, and the date until which the auto-reply is enabled.

In the Forwarding tab, you can configure the address for mail forwarding. In the Signature tab, you can configure a signature for your account, as well as for a domain; you can configure a txt and html signature. In the External accounts tab, you can configure hMailServer to download mail from other mail servers using the POP3 protocol. After the message is downloaded, all server settings will be applied to it, after which the message will be delivered to the local account. The Rules tab allows you to configure rules that work the same as global rules, but apply only to messages. See the Rules section for more details. In the Active Directory tab you can connect an Active Directory account. When a user connects to the server, hMailServer will use Active Directory to validate the user's password. In the Advanced tab, you can specify the user's First Name and Last Name (this data is not used by hMailServer). You can edit IMAP folders and clear the contents of all IMAP folders.

In the Domains-Aliases tab, aliases for mailboxes are configured.

In Domains - Distribution lists, the mailing list is configured. Address - mailing address, messages sent to this address will be forwarded to everyone on the mailing list. There are 3 modes:

• Public - anyone can send letters.
• Membership - only list members can sleep letters.
• Announcements - messages can only be sent from a specific mailbox.

Require SMTP Authentication - if this flag is set, hMailServer will require SMTP authentication for mailing list delivery. If this option is selected, only users with accounts on the server will be able to send email to the mailing list. On the Members tab you can add email addresses. Supports adding addresses from hMailServer (Select...) and importing from text file(Import...).

Rules

In the Rules section, you can enable rules based on the content of the message, for example, you can delete messages with a certain line, or forward messages larger than a certain size. Each rule has a criterion and an action. When you create a rule, you add a criterion that determines which message the rule will be applied to. For example, you can add a criterion that will apply to messages with a specific Message-ID-header. After adding the criterion, we add the action. The action describes what hMailServer should do with the message if it matches the criteria. For example, you can forward, delete a message, or place it in a specific folder.

Settings

In the Settings section, protocol settings are made. You can configure antispam, antivirus (Clamav, required additional installation), enable logging. In Settings-Advanced you can configure Auto-ban, SSL certificate, ports and mail server IP addresses.

Utilities

In the Backup section you can make a backup of settings, domains, messages, and there is also a script that can be added to a daily task. In this section you can also restore data from a backup. In the MX-query section, you can diagnose the MX record of the mail server (analogous to dig MX). In the Server sendout section, you can send a message to a local email address. Diagnostics is another diagnostic tool that checks the connection on port 25, the MX record of the domain.