mail.server.serverX.timeout for IMAP account is somehow set to 29. AFAIR, it is phenomenon reported in other bug(s). So I thought it was already reported bug. But I couldn't find bug about the issue. Phenomenon was observed with next builds. > (a) Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.1pre) Gecko/20090524 Shredder/3.0b3pre > (b) Thundebird 2.0.0.21 > (c) Seamonkey 1.1.15 [steps to produce] 1. Reset mail.server.serverX.timeout via Config Editor or about:config. 2. Restart Tb 3. Open an IMAP folder 4. Click other IMAP folder of same account 5. Repeat step 4 6. Check mail.server.serverX.timeout via Config Editor or about:config => mail.server.serverX.timeout=29 Note: I have Gmail IMAP accounts only. Possibly Gmail IMAP unique issue.

"29 sec" is probably interval of IDLE. mail.server.serverX.timeout is for IDLE? mail.server.serverX.tcptimeout is for timeout value of each account?

http://mxr.mozilla.org/comm-central/source/mailnews/imap/src/nsImapIncomingServer.cpp#636 sets it to 29 minutes, if there's no pref value, a negative value, or a value over 29 minutes, and has done so since May 1999. Could you be more specific about the nature of your objection to that?

Oh, it was "timeoutInMinutes = 29;". It's for next. > http://tools.ietf.org/html/rfc2177 > clients using IDLE are advised to terminate the IDLE and re-issue it at least every 29 minutes to avoid being logged off. I was confused: (a) 29 sec. vs. 29 min. (b) timeout vs. tcptimeout. (c) I thought it's defaulted(no line in prefs.js) if 29 min for interval of IDLE. Thanks for pointing source code. Closing as INVALID.