Send as IMAP account not clearing messages from OUTBOX.

Granted it's an old post but no listed solution to Soho1's issue and it so happens that I have the same problem going on that he first posted of. Anyone ever find the 'fix'?

Generally speaking, my sent messages go right out and into the sent folder if they are small in size. Anything with an attachment goes into this outbox and I play heck getting it sent. My Outlook 2010 goes through a google business IMAP account.

soho1 said:

So, I have been using Outlook 2010 with Exchange and a number of POP accounts. It is not unusual for me to change the FROM account to pick a different email address to show as the sender.

HOWEVER, I recently changed my gmail accounts from POP to IMAP and now, when I try to send as any of them, the outbound message stays stuck in my outbox.

Sending FROM an exchange email works fine and clears the outbox immediately
Sending FROM a POP email works fine and clears the outbox immediately
Sending FROM an IMAP email the message sticks in the outbox and never clears

Funny though (weird not haha) that when I test the account...
File > Account Settings > Change > Test Account Settings
THAT WORKS FINE!

But when I send using New E-mail, THAT MESSAGE STAYS STUCK in the outbox.

Exact same thing going on here HOWEVER... If it's only a short text message, it flies right through so fast you can't see it and is in my sent box. ONLY IF there is an attachment or something that causes for a fairly large email will it get stuck in my outbox. Don't know if I should blame Outlook 2010 or Windows 7. I've contemplated going back to POP but this only recently showed itself as an issue and I'd like to resolve it if possible.

I have soho1's problem exactly. Given that was years ago, surely it's been solved by now but I can't seem to find the answer anywhere on the internet. The strange thing is it was working fine for me up until a few days ago. Some hlp would greatly be appreciated.