Beginning a few weeks ago all email that I create in Outlook stays in the Outbox. Its descriptive text in the Outbox (To, Subject, etc) is in standard font--ie, not italics--as if the message was open somewhere. (Incoming email works fine.)
When I send an email using "Test Account Settings ..." from within Account Settings it works fine, so clearly my settings are correct. Running Office Diagnostics shows no errors.
Vista Ultimate, SP1, all updates current.