Direct Spam
From Computer Tyme Support Wiki
Spam that Bypasses our Filters
So it's been several days and you notice that some spam is still being sent directly to your old server even though all your MX records point to us. So you're asking yourself, "How does this happen? How do they know where my real server is?"
There are two reasons for this. The first is that spammers cache old MX records for far longer than they should. Sometimes it takes weeks for their servers to forget the old MX records. But the other reason is far more common. It's caused when your email server is the same IP address as your domain. For example, if your web server is domain.com and your email server is also domain.com then spammers will sometimes try to send email directly to your server and thus bypassing our filters. But there are things you can do to stop it. but it might take a little work.
- If you have more than one IP address the easy thing you can do is define a new host on another IP and call it something like mail.domain.com. Make that IP accept email from our servers and close the email ports on domain.com and your direct spam problem will go away.
