Using Gmail as Hosted Anti-Spam Filter is the simple and free solution for companies, organizations and individuals who want to get rid of spam without buying and maintaining their own anti spam server or anti-spam software.

How it works
Lack of spam is one of top reasons for Gmail popularity. Obviously, someone processing millions of emails each day should know how to handle SPAM. Use the Google Anti-Spam technology for your own email server. You get a service that is at least as good as SPAMfighter, MessageLabs or Postini (a Google owned company) - for free!

How to use GMail as hosted spam filter

1. Create a GMail account

Let's call it yourname.spamfilter@gmail.com - this account will be the filter between your email server and your local email client.

2. Let GMail process your email

You need to get the email from your email server somehow to GMail. There are two options for this:
(a) Use the Gmail POP3 feature and let Gmail collect your email by polling your email server every few minutes. This works fine, but there are two issues this approach: Gmail leaves SPAM emails with virus attachments on your server and since you need to wait for Gmail to poll your email server, email arrives with a few minutes delay.
(b) Forward the email directly to Google (recommended):

This specific screenshot is from a MailEnable email server, but every email server has such an email-forwarding (redirect) feature.

3. Access the spam-free email

Configure your email client to get the email from your new Gmail account instead of your own email server. All spam stays behind on the Gmail account.

Note that all changes affect only POP3 access. Sending email is done via your own SMTP server, so the Gmail address does not appear in your outgoing emails. All emails still have the format yourname@yourdomain.com.

Alternative solution: Instead of accessing the filtered email via POP3 or IMAP, you can use the Gmail forwarding function to sent the email back to your email server. For this purpose, make two POP3 boxes for each user: user and user_filtered. Gmail gets the email from the user account, filters it and sends it back (forwarding) to the user_filtered account. If you do this, please make sure that "double forwarding" works for you, or use POP3 to get the mails into Gmails (see the list of known issues).

Known problems and solutions:

• GMail does not like exe or VBS files, even inside a ZIP file. Solution: Rename the ZIP file (add .txt) to filename.zip.TXT or encrypt the ZIP file content.
• "Double forwarding" seems not to work with every mail server. You might loose emails if you use it. So you can not forward your email TO Gmail, and forward it back FROM GMail to your mail server (to a different email accoun typically). Workaround: Use POP3 email fetching instead of forwarding to email to Gmail.
• If you use POP3 email fetching please be aware that Gmail stops fetching emails once an error occurred (see screenshot below). To resume the mail fetching, please log in to Gmail, go to settings and click "fetch now". You can automate this process with a web browser macro software like iMacros.

Screenshot of mail fetching stopping after it failed once.

Disclaimer: The Tips & Tricks in the following are based on our knowledge and experience. If you should spot any error and omissions in this text, we would like to hear from you so that we can improve this page.