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. Even more difficult is the fact that the VPS provider can’t really provide a one-size-fits-all set of instructions for configuring the MX and SPF records, since there are many more variables controlled by the VPS administrator. So, suffice to say that email configuration is probably the most dreaded task of most VPS administrators. In fact, many prefer to avoid the pain and suffering altogether and use a third party email provider. However, in my case, since one of my sites sends a lot of forum activity notification emails, I prefer to save on the cost of a third party email provider and do it myself. Read more