I have a forwarding rule with Postfix that forwards all messages to my main email address.
When a spam message is sent to one of my emails, it is forwarded but the sender is shown as being the forwarding domain, not the spammer's domain.
mywebsite.com is hosted on Linode.
email@example.com sends an email to firstname.lastname@example.org
the mail is forwarded to email@example.com
my email hosting (anotherwebsite.com) sees it's spam and sends a message to firstname.lastname@example.org and Linode reports a TOS violation.
I have modified my postfix settings so I now use RBL, but if a message goes through, it may happen again.
How can I prevent this to happen again? Is there some settings to change on Postfix so the original sender is correctly identified?
EDIT: The steps I did to prevent this to happen again are:
- Add RBL checking to Postfix
- Add postgrey to Postfix
- And finally fix the MX record which was incorrect.
I checked with a test email on Spamcop.net and the original sender is correctly identified.