Problem #

External systems are flagging your WHMCS installation’s emails as spam or rejecting them.

Cause #

Usually, this is due to the server configuration. WHMCS email templates should not trigger any standard spam rules.

Solution #

To resolve this, try the following methods:

Use SMTP #

Check whether you can use SMTP rather than PHP mail in the Mail tab at Configuration () > System Settings > General Settings.

Many email providers block PHP mailer scripts as “unverified mail”.

Verify the Sender Address #

Verify that the email address you are sending “from” actually exists on your server, and whether it can send and receive mail normally.

Check for Blacklisting #

Check your mail server’s IP address to verify it is not in any blacklists.

Contact your web hosting or mail server provider for investigation into your IP reputation. They will be able to contact other email providers on your behalf.

Customize Email Templates #

If you suspect that the wording of an email may be triggering a filter, try customizing you email templates so they do not match other WHMCS installation’s emails.

Check SPF and PTR Records #

Verify that your domain has an accurate and strict SPF record setup, as well as a correct PTR record.

Last modified: June 14, 2024