Thunderbird Stopped Working after today's update
Sending of the message failed. An Outgoing server (SMTP) error occurred while sending mail. The server responded: Temporary System Problem. Try again later (10). m30-20020a19435e000000b0048b23c609c9sm158017lfj.102 - gsmtp.
Todas as respostas (1)
Ok so Google are telling you there is a temporary system problem.
Unless you have not updated your connection authentication to use Oauth, I would guess you would just have to give them a while, or post in their support forums asking what that string of numbers actually means. (I have no idea and a google search revealed no results.)