I was sending out marketing/sales emails thru Hubspot today when all of a sudden I couldn't anymore. The "SEND" button was covered by a red circle icon with a line thru it denoting that I the send function was now blocked.
I tried logging out & back in hoping my account would reboot & restore. No-go.
I then clicked "HELP" and chatted with tech support & the agent gained access to my account & couldn't find any error message or problem to explain it.
He recommended my creating this post to help find a solution.