I've read all of the other "stuck in Outbox" issues and as far as I can tell, ours is not related to that.
The issue is that we have messages autogenerated into the Drafts folder of an external sending account (call it "outmsgs@domain.com") and we send special emails out via that account. Multiple users have both Send As and Full Access permissions on that account. Nobody logs in as that account, but it has a mailbox, and those users with access see it in their Outlook as an additional mailbox in the side folder menu.
They can then go into the Drafts folder of outmsgs@domain.com and send those messages.
This worked for years via Citrix and Outlook 2000. We recently switched to Outlook 2010, and now they see everything the same, but when they send it, it just sits there in the Outbox. The visual behavior of it varies (sometimes bold, sometimes italic, sometimes none of the above), but it always stays in the Outbox (it can be manually moved).
BUT - sometimes it actually sends in the background (nearly always), unless you move it before it has sent. There is no way of knowing if it has sent or not, from any visual state. For a single user of 60, theirs never sends when they do this (so I am guessing user behavior).
We very much want this to go back to what it was doing before - the user sends, it works, the end.
Additional data points:
* Exchange 2007 (and Outlook is not using a pst, it is just right off of Exchange - but there is an OST file)
* If you login via webmail as that user (outmsgs@domain.com) then it works fine.
* This happens regardless of whether Outlook is run as normal, or with the "/noextensions" switch (so it is not caused by an add-on).
* Outlook 2010 is not running in cached mode
* It is set to sent immediately, pressing send/receive does nothing (or rather, does nothing help this case)
* If the user is not sending as someone else, regardless of how they create the message, it works fine. But if they add the From field and then change to one of their Full Access users, it will send, but the message stays in the Outbox.
* It being in Citrix doesn't matter - it won't work from any Outlook 2010 instance, but it will work via webmail (Exchange 2007)
*One additional point, not sure this would cause it or not, when we open Outlook 2010, we get two (of the same) error messages regarding our SSL cert on the server (it is a self signed one that shows up for webmail - so the error message is along the lines of what you would expect on a self signed cert.)
We very much want to get this resolved, as it makes it extremely difficult to know if/when things have been sent for that account.