On Sun, 13 Mar 2022 06:50:45 +0800 Bret Busby <bret.busby at gmail.com> wrote: > 550 Access denied - Invalid HELO name (See RFC2821 4.1.1.1) If you don't want to change your system name, you can change what is sent by using the Account Preferences. Go to the 'Advanced' page and set something suitable for 'Domain name'. with regards Paul