Alert emails not setting From header correctly

[remjx]

In the outbound SMTP email request, should the From header field be set to the Monit server domain, or the domain of the username? I am getting this error and after contacting my host they said that the From header is incorrect.

In my example, instead of F=<[email protected]> should it be F=<[email protected]>?

Error returned to monit:

Mail: Mailserver response error -- 550-"Your IP: 18.215.185.21 : Your domain ip-172-26-4-180.ec2.internal is not allowed in header From"

More detailed logs from the host server (Namecheap SMTP server):

2020-04-03 16:35:30 H=ec2-xx-xxx-xxx-xx.compute-1.amazonaws.com (ip-yyy-yy-y-yyy) [xx.xxx.xxx.xx]:57152 F=<[email protected]> A=dovecot_plain:[email protected] rejected RCPT <[email protected]>: "Your IP: xx.xxx.xxx.xx : Your domain ip-yyy-yy-y-yyy.ec2.internal is not allowed in header From"

I also tried Amazon SES SMTP server and get this error:

Mail: Mailserver response error -- 530 Must issue a STARTTLS command first

In my .monitrc file I am just setting Username, Password, Host, and Port. I am able to send e-mail fine through my local Thunderbird client through the SMTP server with these credentials so it seems to be an issue with this plugin.