imap error - 'smtp send operation failed - try again later'
 

trying to get my 770 setup with my imap fastmail account which uses imap. i can get my messages just fine but i cannot send a message. i only get 'smtp send operation failed - try again later' when trying to send a message. fastmail support ssl and i've tried that and non-ssl with the same error message.

any helpful hints or advice out there?