(Well, to be fair, it was partly my own fault too.)

Company policy is that nobody should keep email for more than a year. I haven't done anything about this since we migrated to Exchange/Outlook/Evolution a few months ago, and since I don't have much to do right now I decided it was a good time to look into it.

Create virtual folder. Source: all remote folders. Criterion: date of receipt is earlier than 1 year ago. So far: no problem.

Look at top of virtual folder. Indeed, it appeared to be full of old messages. With six swift keystrokes I highlighted everything in the folder and hit Delete.

About half a second later, it suddenly dawned on me that some of the subject lines that flashed up at the end of the folder looked a bit too familiar to be a year old. I flicked back to my inbox, to discover that its size was a tenth of what it used to be and stuff was missing throughout. Looked for Undo button; Evolution doesn't have one. Cold sweats.

Fortunately, all the mistakenly deleted mail (somewhere over 3000 messages) was still in my Deleted Items folder. Unfortunately, the information about which folder each message came from had been lost. I therefore spent most of the rest of the day finding useful search criteria which identified large groups of messages that I could file back in one of my main folders; and eventually I was down to somewhere under 100 hard-to-classify messages and I sorted the remainder all out by hand.

It transpires that Evolution's ‘date of receipt’ filter is simply broken: if you ask for messages over a year old, you get a whole load of stuff under a year old as well, some things from the same day. Apparently some messages don't get given a receipt date at all, and our best guess is that Evolution therefore assigns them a default date (probably 1st January 1970) for filtering purposes. If you filter on the date of sending, it seems to work much better.

So, much hard work and not a little panic later, everything is more or less back as it started. I repeated the purging process using the date of sending instead of receipt, and this time it did seem to work sensibly. Phew all round; but it's cost me pretty much the entire day to recover from this. I am annoyed.