I followed the procedure to Integrate Amazon SES with Sendmail in Ubuntu as given in the guide. The error log at /var/log/mail.log shows that “AUTH=client, available mechanisms do not fulfill requirements” and “Temporary AUTH failure“. However, it also showed “Message accepted for delivery“. Apr 26 19:35:46 ABC sm-mta[24892]: 33QE5jZl024892: AUTH=client, available mechanisms do not fulfill