User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; de; rv:1.9.0.7) Gecko/2009021910 Firefox/3.0.7 (.NET CLR 3.5.30729) Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.1; de; rv:1.9.1b3pre) Gecko/20090223 Thunderbird/3.0b2 I'm using Cyrus IMAP server and tried to get the IDLE command to work. Using Wireshark if found out that TB 3.0b2 does not use the command and TB2 does. This seems to be, because TB 3.0b2 does not properly detect server support for the IDLE command. Here is the greeting message the server sends when the client connects: * OK [CAPABILITY IMAP4 IMAP4rev1 LITERAL+ ID STARTTLS] server ready Afer the client authenticates, the server confirms the authentication with the following message: 1 OK [CAPABILITY IMAP4 IMAP4rev1 LITERAL+ ID IDLE LOGINDISABLED ACL RIGHTS=kxte QUOTA MAILBOX-REFERRALS NAMESPACE UIDPLUS NO_ATOMIC_RENAME UNSELECT CHILDREN MULTIAPPEND BINARY SORT SORT=MODSEQ THREAD=ORDEREDSUBJECT THREAD=REFERENCES ANNOTATEMORE CATENATE CONDSTORE SCAN IDLE LISTEXT LIST-SUBSCRIBED X-NETSCAPE URLAUTH] Success (no protection) Though the server now reports 'IDLE' as one of his capabilities, TB3 does not detect it. I modified the server to include 'IDLE' capability in the inital greeting message, so that it looks like this: * OK [CAPABILITY IMAP4 IMAP4rev1 LITERAL+ ID IDLE STARTTLS] server ready With this modified greeting message TB3 now detects IDLE support correctly. As it seems to be RFC-compliant for the server to send modified capabilities after authentication and as TB2 correctly detects IDLE capability, this should be ab bug in TB3. Reproducible: Always

Dupe of bug 470650, caused by bug 401293.