This is more of an FYI for anyone using nginx for IMAP proxying.
We have been using 0.5.36 for ages, but decided the other day to upgrade
0.6.31. At first everything seemed to work just fine. However I noticed
when you sent an email via Outlook Express, it would fail to upload the
email to the Sent Items folder on the IMAP server, and report an error
the server terminating the connection. Everything else seemed to be fine
After a bunch of digging about in SSL source, it seemed that the problem
actually Outlook Express disconnecting during the SSL handshake phase.
some suggestions from Igor, it was thought that maybe a change between
and 0.6 series where the SSL session cache was disabled unless
enabled might be the problem.
Some testing seems to show that that is the problem.
By default, 0.6.31 explicitly disables the SSL cache
see http://marc.info/?t=120127289900027&r=1&w=2 for why) unless you add
ssl_session_cache line (see
It seems that there’s some interaction between OpenSSL and Outlook
that one of them doesn’t like. Adding any sort of session cache seems to
the problem. (Even if it’s only a local one in a multi-process model,
in theory should not necessarily help at all)