There are a large variety of different IMAP servers in use and while they all meet the basic requirements in RFC 3501 there are a lot of optional features that can greatly affect the resulting capabilities.

The two key things we are looking at now are the result of a capabilities request and the permanent flags report from a select (if it lists \* then we can setup our own flags).

The servers we have information about are

* OK [CAPABILITY IMAP4REV1 NAMESPACE ID AUTH=PLAIN AUTH=LOGIN UIDPLUS STARTTLS ACL METADATA] servername.example.com IMAP4rev1 Citadel 7.22 ready
b select INBOX
* 207 EXISTS
* 8 RECENT
* OK [UIDVALIDITY 1] UID validity status
* OK [UIDNEXT 44659] Predicted next UID
* FLAGS (\Deleted \Seen \Answered)
* OK [PERMANENTFLAGS (\Deleted \Seen \Answered)] permanent flags
b OK [READ-WRITE] select completed
c CAPABILITY
* CAPABILITY IMAP4REV1 NAMESPACE ID AUTH=PLAIN AUTH=LOGIN UIDPLUS STARTTLS ACL METADATA
c OK CAPABILITY completed

* OK [CAPABILITY IMAP4rev1 UIDPLUS CHILDREN NAMESPACE THREAD=ORDEREDSUBJECT THREAD=REFERENCES SORT QUOTA IDLE ACL ACL2=UNION STARTTLS] Courier-IMAP ready. Copyright 1998-2004 Double Precision, Inc.  See COPYING for distribution information.
a OK LOGIN Ok.
* FLAGS (NonJunk \Draft \Answered \Flagged \Deleted \Seen \Recent)
* OK [PERMANENTFLAGS (NonJunk \* \Draft \Answered \Flagged \Deleted \Seen)] Limited
* 10 EXISTS
* 0 RECENT
* OK [UIDVALIDITY 1085611025] Ok
* OK [MYRIGHTS "acdilrsw"] ACL
b OK [READ-WRITE] Ok
* CAPABILITY IMAP4rev1 UIDPLUS CHILDREN NAMESPACE THREAD=ORDEREDSUBJECT THREAD=REFERENCES SORT QUOTA IDLE ACL ACL2=UNION
c OK CAPABILITY completed

* OK mail8.hotbox.ru Cyrus IMAP4 v2.2.3 server ready
b select INBOX
* FLAGS (\Answered \Flagged \Draft \Deleted \Seen)
* OK [PERMANENTFLAGS (\Answered \Flagged \Draft \Deleted \Seen \*)]
* 21 EXISTS
* 20 RECENT
* OK [UNSEEN 2]
* OK [UIDVALIDITY 1078330095]
* OK [UIDNEXT 379]
b OK [READ-WRITE] Completed
c capability
* CAPABILITY IMAP4 IMAP4rev1 ACL QUOTA LITERAL+ MAILBOX-REFERRALS NAMESPACE UIDPLUS ID NO_ATOMIC_RENAME UNSELECT CHILDREN MULTIAPPEND BINARY SORT THREAD=ORDEREDSUBJECT THREAD=REFERENCES ANNOTATEMORE IDLE LOGINDISABLED
c OK Completed

[email protected]:~> telnet imap.ktb.net 143
Trying 198.175.228.193...
Connected to imap.ktb.net.
Escape character is '^]'.
* OK dovecot ready.
a login myuser mypass
a OK Logged in.
b select INBOX
* FLAGS (\Answered \Flagged \Deleted \Seen \Draft)
* OK [PERMANENTFLAGS (\Answered \Flagged \Deleted \Seen \Draft \*)] Flags permitted.
* 315 EXISTS
* 122 RECENT
* OK [UNSEEN 1] First unseen.
* OK [UIDVALIDITY 1083632541] UIDs valid
* OK [UIDNEXT 12452] Predicted next UID
b OK [READ-WRITE] Select completed.
c capability
* CAPABILITY IMAP4rev1 SORT THREAD=REFERENCES MULTIAPPEND UNSELECT LITERAL+ IDLE                    CHILDREN LISTEXT LIST-SUBSCRIBED
c OK Capability completed.

* OK Microsoft Exchange IMAP4rev1 server version 5.5.2654.50 (wlvexc00.diginsite.com) ready
b select INBOX
c capability
d logout
* 22576 EXISTS
* 0 RECENT
* FLAGS (\Seen \Answered \Flagged \Deleted \Draft)
* OK [PERMANENTFLAGS (\Seen \Answered \Flagged \Deleted \Draft)]
* OK [UNSEEN 50] Is the first unseen message
* OK [UIDVALIDITY 54805] UIDVALIDITY value.
b OK [READ-WRITE] SELECT completed.
* CAPABILITY IMAP4 IMAP4rev1 IDLE LITERAL+ LOGIN-REFERRALS MAILBOX-REFERRALS NAMESPACE AUTH=NTLM
c OK CAPABILITY completed.
* BYE Microsoft Exchange IMAP4rev1 server version 5.5.2654.50 signing off

* OK Microsoft Exchange Server 2003 IMAP4rev1 server version 6.5.6944.0 (stbowa02.stb.sun.ac.za) ready.
b OK LOGIN completed.
* 8 EXISTS
* 0 RECENT
* FLAGS (\Seen \Answered \Flagged \Deleted \Draft $MDNSent)
* OK [PERMANENTFLAGS (\Seen \Answered \Flagged \Deleted \Draft $MDNSent)] Permanent flags
* OK [UNSEEN 1] Is the first unseen message
* OK [UIDVALIDITY 13888] UIDVALIDITY value
c OK [READ-WRITE] SELECT completed.
* CAPABILITY IMAP4 IMAP4rev1 IDLE LOGIN-REFERRALS MAILBOX-REFERRALS NAMESPACE LITERAL+ UIDPLUS CHILDREN
d OK CAPABILITY completed.
* BYE Microsoft Exchange Server 2003 IMAP4rev1 server version 6.5.6944.0 signing off.

* OK [x.x.x.x] IMAP4rev1 Mercury/32 v4.01a server ready.
a login username password
a OK LOGIN completed.
b select INBOX
* 56 EXISTS
* 0 RECENT
* FLAGS (\Deleted \Draft \Seen \Answered)
* OK [UIDVALIDITY 1096732164] UID Validity
* OK [UIDNEXT 1102] Predicted next UID
* OK [PERMANENTFLAGS (\Deleted \Draft \Seen \Answered)] Settable message flags
b OK [READ-WRITE] SELECT completed.
c capability
* CAPABILITY IMAP4rev1 X-MERCURY
c OK CAPABILITY complete.

* OK Messaging Multiplexor (iPlanet Messaging Server 5.2 HotFix 1.26 (built Mar 31 2004))
* OK [PERMANENTFLAGS (\Answered \Flagged \Draft \Deleted \Seen NonJunk Junk XOPL-3 \*)]
* CAPABILITY IMAP4 IMAP4rev1 ACL QUOTA LITERAL+ NAMESPACE UIDPLUS CHILDREN LANGUAGE STARTTLS XSENDER X-NETSCAPE XSERVERINFO  

* OK [CAPABILITY IMAP4REV1 LOGIN-REFERRALS STARTTLS AUTH=LOGIN] leto IMAP4rev1 2001.315rh at Mon, 31 May 2004 11:06:55 +0200 (CEST)
a LOGIN 
a OK [CAPABILITY IMAP4REV1 IDLE NAMESPACE MAILBOX-REFERRALS SCAN SORT THREAD=REFERENCES THREAD=ORDEREDSUBJECT MULTIAPPEND] User xy authenticated
b SELECT INBOX
* 3 EXISTS
* 0 RECENT
* OK [UIDVALIDITY 1084972038] UID validity status
* OK [UIDNEXT 39] Predicted next UID
* FLAGS (\Answered \Flagged \Deleted \Draft \Seen)
* OK [PERMANENTFLAGS (\* \Answered \Flagged \Deleted \Draft \Seen)] Permanent flags
b OK [READ-WRITE] SELECT completed
c CAPABILITY
* CAPABILITY IMAP4REV1 IDLE NAMESPACE MAILBOX-REFERRALS SCAN SORT THREAD=REFERENCES THREAD=ORDEREDSUBJECT MULTIAPPEND LOGIN-REFERRALS STARTTLS AUTH=LOGIN
c OK CAPABILITY completed
D LOGOUT
* BYE leto IMAP4rev1 server terminating connection
D OK LOGOUT completed