Emails generated from within WordPress often end up in your spam or junk folder, This service helps you sort that out. The default of this service can often be enough to solve your problem.
When using the default PHP mailer in WordPress, especially on shared servers, emails will often be set to spam or junk by receiving email systems. This can be very frustrating and important notifications can be missed by you or your clients.
Why does this happen? One problem is the “envelope sender” not being set, and many hosts will recommend that you install a plugin to set the “envelope sender”, this is the main purpose of this service is to address this common issue.
Along with setting the “envelope sender” this service also displays your Sender Permitted From (SPF) and checks your server IP is in the SPF record, if there is one.
Support is for the the default PHP mailer only.