On Sat, 10 Aug 2013, Arne Berglund wrote:
You mentioned that you have 3 servers running, I wonder if the loss of session is because when moving from place to place your users are changing servers? No idea if that's a possibility, as I have no experience with clustering of this type.
No, logins sessions are attached to a single server (so the squirrelmail caching IMAP proxy can work to its best effect). The only particularly unusual thing about our setup is that we are using memcached for session storage, which Thomas indicated was new when I asked a few weeks back.
This means that sessions are expire immediately at the end of the session lifetime (plus a 60 second fudge factor that I have added) rather than being garbage collected asynchronously some time later.
However at the moment this is all just a best guess on my part to explain two reports of the Send button failing to respond, and my own observation that I see exactly the same effect if the session cache entry is left to expire. I could be barking up the wrong tree altogether.