I am trying to understand the NDR messages setup beforehand by someone else.
I sent 2 test emails from outside the organization, above the set limit for attachments.
The limit is set to 11MB.
I sent a 13MB email and got a NDR from - Mail Delivery System title 'Undelivered Mail Returned to Sender'
I sent a 12MB email and got a NDR from - Postmaster@xxx.com title 'Undeliverable: subjectname'
Can someone explain where the emails are coming from, and how the system is differentiating between the 2 different emails? Basically, how come one email is from postmaster and other is from mail delivery system.
We would like the postmaster message as it looks better and has explanation.