One day my bulk-mailer python script threw (I mean raised) SmtpServerDisconnected error, it surely was smtplib’s “fault”. So I tried to make it send_mail only to my own address. The error gone. Means that it should be caused by it having too many recipients.
So instead of sending to [VeryLongList], i made it to send_mail for each in [VeryLongList] instead. And it successfully sent the
spam notification mails.