@Vincent-TP You can call it a "feature request" if you like, but in my opinion this is a bug report - the SMTP client in the Omada controller software is clearly not RFC2821 compliant and this is why...

Just adding to the above, I have just verified that Google's SMTP relay does indeed immediately close the connection when localhost is used with the EHLO command: liamriley@eros ~ % nc...

We use google workspace for our business email, so I'm trying to use smtp-relay.gmail.com to send email notifications from my Omada controller, as described here:...