Dramatic headline eh?
I had to block my email server yesterday after I was sent an email saying my email server was set up as an open relay and propagating spam messages. When I checked things out, I was shocked to find that the system had sent out almost 20,000 unsolicited emails! WOW!
For those who need the plain english description, an open relay means that spammer@domain1.com can send mail to victim@domain3.com by connecting through openrelay@domain2.com. This means that the recipient (victim@domain3.com) will not see that the email is coming from spammer@domain1.com, it’ll actually look like it’s coming from openrelay@domain2.com.
It turned out it was a setting I had overlooked when setting up my email server. Once I fixed that and cleaned out the other 8,000 emails that were waiting to be delivered, I was able to bring it back online. I then filled out the online form at Open Relay Database to retest me. They were the ones who originally sent me the email, so I was glad to have that cleared up.
Turns out, the open relay issue is probably why I haven’t been able to successfully send email to people on several ISPs.