Google Mail supports IMAP IDLE

by Volker Weber

Maybe this is old news to you. I just wasn't sure whether Google Mail supports IMAP IDLE, so I asked the server:

openssl s_client -crlf -quiet -connect imap.gmail.com:993

to which it replied:

depth=1 /C=US/O=Google Inc/CN=Google Internet Authority
verify error:num=20:unable to get local issuer certificate
verify return:0
* OK Gimap ready for requests from xx.xxx.xxx.xx l19if11972848fgb.2

Then I asked:

C01 CAPABILITY

C01 is arbitrary, you can also say a001 or whatever you like. In any case, the server said:

* CAPABILITY IMAP4rev1 UNSELECT IDLE NAMESPACE QUOTA XLIST CHILDREN XYZZY
C01 OK Thats all she wrote! l19if11972848fgb.2

IDLE. That means you get instant delivery of your Google Mail, if you have an email client capable of IMAP IDLE, like Mail.app on the Mac for instance:

mailappimapidle

Comments

Well this makes sense. I've noticed how my Thunderbird client instantly shows new GMail e-mails (for example when I conduct a Web transaction with notification). Now I know why.

Arthur Fontaine, 2009-05-28

I thought that this was well-known for a long time. Or wasn't it?

Daniel Haferkorn, 2009-05-28

yeah, the BlackBerry Internet Service for example makes heavy use of this feature because emails are getting a lot faster to the device

Thomas Einwaller, 2009-05-28

Daniel, I wasn't sure. And Thomas, I don't think BIS uses IMAP IDLE.

Volker Weber, 2009-05-28

BIS doesn't use IMAP IDLE.

BTW Volker, did you notice the Edgar Allan Poe allusion when you logged out of IMAP with OpenSSL?

Chris Linfoot, 2009-05-28

I did notice the sentence but do not see an allusion to Edgar Allen Poe.

Volker Weber, 2009-05-28

BIS does indeed use IMAP idle.

Abdelkader Boui, 2009-05-28

C01 LOGOUT
* BYE Logout Requested l19if11972848fgb.2
C01 OK Quoth the raven, nevermore... l19if11972848fgb.2
read:errno=0

Chris Linfoot, 2009-05-28

@Abdelkader Boui - My bad. You are correct.

Chris Linfoot, 2009-05-28

Ah, I did not do a logout. And if I did it would have been C02. ;-)

Volker Weber, 2009-05-28

Abdelkader, while I reported it last year, I have not found any hard evidence that this is the case. RIM seems to collaborate with big ISP on delivering mails in a similar fashion, but I cannot really imagine they would be keeping TCP connections open for every single mailbox to get this notification.

Volker Weber, 2009-05-28

End of last year, when Volker reported it, it worked, but I noticed approx half a year ago, that "immediate delivery" (i.e. IMAP IDLE) had stopped working. That may (or may not) be a feature of my BIS accounts, in any case currently BIS IMAP to Gmail doesn't do IDLE.

Jan-Piet Mens, 2009-05-28

I am trying to get an official confirmation that IMAP idle is used by BIS. As soon as I have the answer, I will report back. There was an article on BTSC about the IMAP idle support, but it isn't accessible anymore.

Abdelkader Boui, 2009-05-28

This feature is available only unter OSX 10.5. Mail Client. (Every Version newer than Mail 2.1.3)

Ingmar Melchert, 2009-05-29

Official confirmation from a human isn't worth much. I prefer official confirmation from my dovecot rawlogs.

e EXAMINE "inbox"
f UID FETCH 39912:* (UID FLAGS)
i IDLE
DONE
f UID FETCH 39914:* (UID FLAGS)
i IDLE

yes, the BIS does send IDLE commands. And yes it is nice and fast. And I did ask for IMAP IDLE in the Notes partner forum a long long time ago and as far as I am aware IBM is being IDLE and Domino doesn't support it.

Alan Bell, 2009-05-30

IMAP is a checklist feature in Notes and Domino. You are not supposed to actually use it.

Volker Weber, 2009-05-30

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