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Set Up Postfix to Relay Outbound Messages Through SpamHero

If you have a Postfix email server, you can configure your email server to Relay your outbound messages through our outbound service.

  • First, login to your SpamHero account and go to Outbound > Outbound Settings and check the Enable outbound smart host relay option under the Smart host setup heading and set up a password. Your username is your domain name.
  • Create a password file named /etc/postfix/sasl_passwd and enter the following information, but replace user with your domain name, and replace password with the password you set in the previous step:


  • Hash this file for Postfix:


  • Edit your Postfix main.cf file. This may be located at /etc/postfix/main.cf, and add the following lines:


  • Reload Postfix:


Don't forget to add our SPF "include" record to your domain's DNS, to help with delivery:

Should I include SpamHero's IPs in my domain's SPF record?

If you are a reseller, ask about our private label version of the SPF include.

If you see warnings such as "warning: SASL authentication failure: No worthy mechs found," or "SASL authentication failed; cannot authenticate to server ... no mechanism available," then you may need to install additional packages.

For CentOS, you may need to install cyprus-sasl and cyprus-sasl-plain (you may also need cyrus-sasl-lib, but our test on CentOS 7 didn't seem to require that package).  On other systems, you may need libsasl2-modules.

If you see errors in your Postfix logs such as the following:


This may indicate that you need to update your CA bundle.

If your mail server signs outbound messages with DKIM (Domain Keys Identified Mail), be sure to exclude the Received header lines from the signature. Our servers strip out the Received header lines before relaying because some mail hosts reject messages when the originating IP is on a blacklist.

Last updated June 2, 2022