From Wikitech
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== Design decisions == | == Design decisions == | ||
; Black box mail system, no user shell logins : Few users would make good use of this anyway. Greatly simplifies network and host security, allows the use of some (non-critical) non-standardized extensions between software components for greater performance, interoperability and features because it doesn't have to support whatever shell users might install to access things directly. | ; Black box mail system, no user shell logins : Few users would make good use of this anyway. Greatly simplifies network and host security, allows the use of some (non-critical) non-standardized extensions between software components for greater performance, interoperability and features because it doesn't have to support whatever shell users might install to access things directly. | ||
Revision as of 12:21, 21 April 2007
Contents |
Design decisions
- Black box mail system, no user shell logins
- Few users would make good use of this anyway. Greatly simplifies network and host security, allows the use of some (non-critical) non-standardized extensions between software components for greater performance, interoperability and features because it doesn't have to support whatever shell users might install to access things directly.
- IMAP only, no POP3
- IMAP has good client support nowadays, and for a large part solves the problem of having multiple clients. Also backups can be done centrally on the server side, and multiple folders with server side mail filtering might be supported.
- Support for mail submission
- Through SMTP authentication we can allow our users to submit mails through the mail server, without them having to configure an outgoing mail server for whatever network they reside on. Can support multiple ports/protocols to evade firewalls.
- SSL/TLS access only, no plain-text
- Although client support for this is not 100% yet, especially on mobile devices, the risks of using plain-text protocols is too high, especially with users visiting conferences and other locations with insecure wireless networks.
- Quota support
- Although we can set quotas widely especially for those who need it, quotas should be implemented to protect the system.
- Spam and virus filtering
- Is unfortunately necessary. Whether this should be global or per-user is to be determined.
- Web access
- Some form of web-mail would be nice, although not critical at first and can be implemented at later stages.
- Backups
- At least daily, with snapshots.
- Cold failover
- Setting up a completely redundant system is probably a bit overkill at this stage, but we should make it easy and quick to set up a new mail system on other hardware in case of major breakage.
- Documentation
- Although not all aspects of the involved software can be described of course, the specifics of the Wikimedia setup should be properly documented and HOWTOs for commonly needed tasks should be provided.
Software and formats used
- MTA
- Exim : Great flexibility, very configurable, reliable, secure
- IMAP server
- Dovecot : Fast, secure, flexible
- Maildir
- Safe, convenient format, moderately good performance, good software support
- Password and user databases
- To be determined. Important aspects: easy maintenance, good software support, replication support. Possible options:
- passwd-file - Simple field-separated text file, non-indexed. Supported by both Exim and Dovecot.
- sqlite - Indexed file format, powerful SQL queries, no full-blown RDBMS needed. Supported by both Exim and Dovecot.
Old Wikimedia email setup
- postfix, mailman, OTRS, spamassassin on goeje
- mail.wikimedia.org <- service ip/name for mail
- secure.wikimedia.org <- service ip/name for OTRS
- ticket.wikimedia.org <- service name for OTRS, redirects to secure.wikimedia.org currently
- sendmail on most other machines (apaches)
- internally in pmtpa they forward to smtp.pmtpa.wmnet, which relays to the external world.
How to make an email alias
On goeje:
vi /etc/postfix/aliases newaliases postfix reload
It takes up to 15 minutes until the secondary MXes accept mail for new aliases.
