That error message suggests that a lot of email is being sent on your account. That might suggest that your account has been compromised. The general advice in this stock answer might help you...
Reset email password
Also, are you sending a new item or replying to one you have received?
Re: Sending issue.
I had thought the 'spam' thing was because, in frustration with the 'send' problem, I'd tried to send same message too many times. But it looks to me as if there's a problem with outgoing servers.