How do spammers find my mail server?

To get around your spam filter, spammers will try to send directly to your mail server. They use a variety of tactics, such as:

• Caching old MX records well after they have changed
• Sending directly to your website IP address
• Sending directly to your mail. sub-domain
• For more, see: Spam getting around the filter?

Tips for shared mail servers

If you are using a shared hosting provider, typically your

• Check to see if your provider's control panel gives you the ability to create a custom mail filter to block all messages that do not contain
  in the header.  If this is an option in your control panel, this will be the most effective way to prevent spam from getting around our filter.  If you're not sure if this is an option for you, let us know what control panel you're using, and we can check to see if this is an option for you.
   
• Create a filter in your email software to send email that does not contain
  in the raw headers to your junk folder.  Check the documentation for your email software on how to create this filter.  If users on your domain send email through your mail server, note that it will not contain this header and another filter will be needed to whitelist email from your own domain. Note that this solution is only useful if you get email on your PC only since most email applications on mobile devices do not have the ability to create custom filter rules yet.
   
• Set up private email addresses on your hosting account that are not published.  Create forwards for your public addresses in SpamHero to these private accounts.  Set up your email software to pick up and send email through these private accounts, but using the public addresses as the "reply-to" address on these accounts so that others only see your public addresses.  Shut down the public addresses with your hosting provider.  For a more detailed version of these instructions, see: Alternative method of preventing spammers sending spam directly to your server.
   
• If none of the above options are possible, then changing the IP assigned to your domain might work.  This solution is only effective if your shared host does not have all email for their clients going to the same mail host. Even if you can change your domain's IP, some spammers will find the new IP using the "A" record in your DNS records, so this solution isn't normally recommended.

Tips for dedicated mail servers

If you have a dedicated mail server you likely have a few more options available to you and we've created a separate document:

Preventing Spammers from Sending Email Directly to Dedicated Mail Servers