Compression of stored e-mail

We’ve recently upgraded the Dovecot mail server software we use, and a new feature allows us to do something we’ve wanted to do for a long time: compress stored mail on our servers. We’ll be starting to do that over the next few weeks.

Compressing mail happens invisibly on our end. It makes no difference to what you see in your mail program, and you don’t need to do anything or worry about it.

The benefit to our customers is that it saves 20-30% of the disk space the messages use. While most of our customers don’t store very large amounts of mail on our servers, those who do will see their disk space usage drop by 20-30%.

In the very unlikely event that you don’t want your server mail files compressed — because you’ve installed your own software that reads the raw “maildir” text files, instead of using POP/IMAP/Webmail to access it — our page about mail storage explains how to disable it.

Update: A later 2015 upgrade to our mail system allowed compression of mail “in transit” before it’s delivered, which means compression can’t be disabled anymore. However, no customer ever actually disabled it under the original scheme, so this should not cause any problems.