MAG's Mail Server
CentOS 7 on a the fred.mag-uk.org virtual server
This server uses the following Open Source components
This is the most widely used mailing lists server component. It is the one MAG has been using for 15+ years for all of the mailing lists used by the group. The plan is to simply transplant the mailing lists from the central server to the mailbox machine and continue using them from there. All of the existing settings and archived messages will move across.
The difference will come with the way that the subscriber lists are populated. All of the local group mailing lists are, at the moment, populated and maintained by hand, by either the group reps or webmasters, or by the systems administrators. A system is currently in development that will hand off this task to the staff at central via a new web user interface that links the Internet Services with the Membership Database.
This is the Industry Standard email server service. It allows many additional optional features and we have enable a good number of them.
This is the Industry Standard IMAP/POP mail server, which allows some quite sophisticated plugins, see below. This is the same component used on the central mail server.
Dovecot was used on the current mail server at central, but with this installation advantage is being taken of more recent developments; particularly in that this installation supports the Internet Standard "Sieve" system for user controlled mail filtering. With Sieve you can set certain mails to go straight into a different folder as soon as they arrive, based on sender, or subject, or indeed pretty much anything; and set up a vacation message if you need to.
This is a very popular email system framework. Its job is to tie together and orchestrate other mail service components into a coherent functional whole. The existing MAG mail server has been using this component since day one.
This is a very popular spam filter component. On central.mag-uk.org it was used as a component of the MailScanner system, but on mailbox.mag-uk.org it will be used within postfix itself, enabling the mail server to refuse to even accept spammy mail, thus relieving the rest of the system of the burden of handling it through to the user's "Junk" folder. See The Spamass-Milter project. Instead of accepting the mail without checking its spammyness, and then processing it through the filter and categorising it. The milter (aka Mail Filter) stops the mail server during the reception of every mail for a second or two, while it checks for spammyness and if it is too bad, it simply refuses the reception of the mail with a permanent error. This will have a number of advantages beyond keeping spammy messages completely away from the members in terms of longer term spam prevention.
DMARC is the latest attempt to shore up standard internet email against abuse. For further information, please see: The DMARC Project and The OpenDMARC Project. It is implemented as another "Milter", running directly inside the mail server to scan and categorise emails before they are even accepted onto the system. It also includes provisioni to summarily rejecty mails that fall foul of this mechanism, but this is early days as yet, so the result of the DMARC analysis is fed through to MailScanner and Spamassassin to inform their decision making.
DKIM is a popular email signing mechanism now in use by most of the major players in the internet email game. See DKIM Page and The OpenDKIM Project for further information. On the MAG servers this is implemented using another Milter plugin to Postfix, meaning that it could reject signed but corrupt mails before they even enter MAG's mail system, but this is not being done as yet as there are some issues with the way 3rd party providers implement DKIM with mailing lists, which would lead to MAG rejecting a whole category of good, but badly processed emails.
MailWatch is a Web GUI that sits on top of MailScanner and allows monitoring of email classification and the production of reports. Every mail that gets processed leaves a record in the MailWatch database and can subsequently be queried. It preserves the headers of those mails, but for obvious reasons does not record the body text.
RoundCube is an industry standard email web UI aka "Webmail". It can be accessed at https://mailbox.mag-uk.org/webmail/. It is intended as an emergency service for when members lose/break/flush/drop in beer their smartphone or their PC blows up; providing access to their MAG mailboxes while a new device is being set up.