Thanks Antoine. I've attached an updated patch. 

>> 
- the keyfile / certfile pair and the context parameter should be mutually exclusive (see e.g. the POP3_SSL constructor in Lib/poplib.py)
[Sijin] - Yes, Thanks, I don't know why I didn't check POP3 impl before.

- I don't think the remote test server used in test_imaplib supports client certificates, it probably just ignores them; that said, it's better than nothing
[Sijin] - Agreed, I don't think the server supports client certificates, but at least we are able to test that the connect still works. Maybe we should open a new task to have a remote server that supports client certificate connections? We could use that in test cases for other SSL related modules.

- you have a misindented line in test_logincapa
[Sijin] - Fixed.

- since we're using a remote, third-party test server, it may be better not to do any spurious connects (in the current patch, a first connection is established in the setUp() and then ignored since another one is established in the test body)
[Sijin] - Fixed.

- you need to update the documentation in Doc/library/imaplib.rst
[Sijin] - Done. Also added some corresponding info in the poplib and docs for poplib.