outlook email on phone gets stuck in outbox and never sends
I've had this happen twice, a year apart, and I forget in between times!
Look at your oldest email in Outbox limbo. It may have a huge attachment (photo, etc) or some other issue with it. delete it. the rest should all get sent immediately.

You will then get a bunch of WTF emails from friends about your "see you in 5" emails from a month ago, so you may want to delete those before the oldest email.

Hope this helps!