Actually, I have seen this error before, but I always got around it by pushing send/receive all again. Today, I’m actually getting a message back saying my email is undeliverable and then that error appears after each email address. ‘firstname.lastname@example.org’ - 5.7.1 <email@example.com>… Relaying denied: You must check for new mail before sending mail. I am trying to send them in a BCC. It worked fine with everyone in the TO field but I don’t want to do it that way!
I cannot get around it anymore. I am using a free license which incidentally often deregisters itself and there are no updates available.