[Evolution-hackers] IMAP server capabilities

[Not Zed <notzed ximian com>]

Evo needs to know if its processed a message before on IMAP - so it can
more reliably do filtering and a few other things.

I think at this point the solution would be to set a custom flag on the
server, but it depends on how many servers out there don't support
custom flags, since in this case we can't just fudge it with local
copies of flags.  I think it would be very few that don't.

Any idea how many servers don't support custom flags?

You can tell from the initial login sequence to an imap server:

* OK [PERMANENTFLAGS (\* \Answered \Flagged \Deleted \Draft \Seen)]
Permanent flags

When it includes \*, as above.