Out website has a registration form which sends a copy of the form submitted to both the registrant and the system admin.
Lately, I have been receiving a number of "Undelivered Mail Returned to Sender" emails including the error below (in code box).
I'm pretty new to Sendmail so what do I need to do to resolve this?
This is the Postfix program at host 112233-www1.web.mydomain.com.
I'm sorry to have to inform you that your message could not be delivered to one or more recipients. It's attached below.
For further assistance, please send mail to <postmaster>
If you do so, please include this problem report. You can delete your own text from the attached returned message.
The Postfix program
<firstname.lastname@example.org>: host domain-smtpin.mail.rr.com[18.104.22.1684] said:
554 5.1.8 - Domain of sender address email@example.com
does not exist (in reply to MAIL FROM command)