IMAP Support in Outlook 2010

Microsoft Outlook can be used to access email using the Internet Standard IMAP protocols, and the older POP protocol. In Outlook 2010, Microsoft made a number of improvements to IMAP support. Both the descriptions of what has been done and the extensive comment in this blog are interesting.

Broadly, IMAP in Outlook 2010 works reasonably, and performance against IMAP accounts feels slightly better than Outlook 2007. However, we have observed client hangs (needing product restart) and slowness interacting with IMAP servers.

The improvements to deletion, by moving messages to a "trash" folder on the server, are good. This deletion also works cleanly with Outlook rules set up to delete selected messages as they arrive.

The async download of messages is a good thing. It is a pity that they don't also download the message structure so that the user can select attachments to download, which would be helpful with large attachments on a slow link. It is disconcerting to see a message start off without an attachment and then have the attachment appear later. There is a bug with calendar items, whereby you can only see the message as a calendar item the second time it is opened (after the attachment is downloaded).

For IMAP users, there seems to be a regression in using TNEF (the Microsoft internal format, that non-Exchange users see as "winmail.dat" attachments) rather than MIME, and it does not appear possible to suppress this for message forwarding as attachment and at some other times.

For use in a mobile environment, where links are not always as fast as they should be, it is a pity that Outlook is not making more use of advanced IMAP and LEMONADE features to improve the user experience.

IMAP support in Outlook 2010 has improved, but Microsoft could do very much more.

...Steve Kille. Steve is a periodic contributor to Ferris Research. He is also CEO of Isode, a messaging and directory server software vendor.

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