2
votes
1answer
565 views

Prevent mail server (sendmail) used to backscatter

Hi I recently got an email from Amazon, saying that my EC2 instance is sending spam. So what they say is my mail server is receiving email for a non-existing user and therefore bounces the email back ...
0
votes
1answer
181 views

Blocking External Mail Sent w/ Spoofed Email Address

We recently got an email from an outside server that had a spoofed "From:" header that was the email address of one of our users. Is there a way to have sendmail reject emails coming in from an ...
0
votes
1answer
386 views

How to avoid sendmail relay domains spoofing

I have a bunch of domains as relay domains at my sendmail config, i noticed that some dirty botnet is using dns spoof to be able to send emails using those relay domains. How it works: a domain ...