Configuring and Debugging My Linode VPS with an SPF Record that Passes the Gmail Spam Filter
I have been having no end of problems with my outbound email messages sent by my Drupal sites since I switched from shared hosting to VPS hosting. A typical shared host offers a well configured SMTP server with documentation about how to configure the MX and SPF records. On the other hand, a VPS requires the administrator to install and configure the mail transfer agent, which can be surprisingly complex.