E-mail changes 2009-01-13

What changes?

2 changes will be done on this date

• Change of software from UW-IMAP to Dovecot This itself should not affect much, other than being much faster (except on first access due to it rebuilding indexes of the mailboxes).
• The old UW-IMAP software by default searches for mail in the whole home directory, so I can for instance store my mail in the public_html directory if I want to. To make it easier to separate what is mail and what is not, we are moving all mail related things into the Mail directory in the homedir. This separation makes it easier for future system changes that could make things faster/better.

Technical details

UW-IMAP stores a list of "subscribed" mailboxes in ~/.mailboxlist which can contain something like:

INBOX
courses08
courses07

Our Dovecot is configured to only look for additional mailboxes (other than INBOX) in the Mail directory, and it stores its subscriptions in Mail/.subscriptions. We will copy this over from the ~/.mailboxlist which has the same format. If Dovecot looks in the subdirectory Mail for the mailboxes courses08 and courses07, they won't be found since they are outside that directory.

Dovecot stores indexes of the mailboxes for faster access. These will be rebuild on first access and if the mailbox is externally modified. In other cases, they should provide a good speedup.

Moving mail automatically

Our Dovecot is also configured to move mail from outside Mail into this directory on access. Example:

• You are using Thunderbird with all default configuration, which gives you the mailboxes:
  • INBOX
  • Drafts
  • Sent
  • Templates
• Unless otherwise configured ("Mailbox path" set according to our recommendations), these will be stored directly in your homedir (/home/c83/c83xyz/Sent vs H:\Sent for instance).
• New server only looks in /home/c83/c83xyz/Mail/ for mail.
• You start up Thunderbird after the change and it tells the server to look for just "Sent" without any path information. It looks in /home/c83/c83xyz/Mail/Sent, but it's not there.. It's at /home/c83/c83xyz/Sent
• Our little modification will move the file from /home/c83/c83xyz/Sent to /home/c83/c83xyz/Mail/Sent and continue as usual.
• Next time your Thunderbird asks the server for Sent, it has already been moved into the Mail subdirectory and it just works.

Possible problems

One failure scenario is as follows:

• You have a mailbox ~/courses/courses08
• You have a mailbox (which is a file) in ~/Mail/courses
• You try to access the mailbox courses/courses08
• Here, the system will try to create a subdirectory called courses in ~/Mail, but that is already occupied with a file/mailbox called courses.
• IMAP server will fail and say that courses/courses08 is unavailable.

Remedy: Either rename the accessible mailbox called courses and then try accessing the courses/courses08 again, or manually move it into the Mail subdirectory with a new name.

Failures are logged, and we will monitor them actively the near period after the change and contact people which are affected. Contact us if you run into problems, support@cs.umu.se

Automatic mail filtering (procmail)

If you are using automatic mail filtering with for instance procmail and you store your mail somewhere other than under ~/Mail/, you want to change this to ~/Mail/.