550 5.7.1 Relaying to <email@address.com> denied (authentication required)

Below are two options to look at in the Administration Console for a possible misconfigured setting.

  1. Verify the relay control settings within the Administration Console. Navigate to Configuration > SMTPSimple Mail Transport Protocol - An internet standard used for email transmission across IP networks. Server > Relay Control.

A brief description of each option:

  1. Verify the SMTP service has not been restricted to an IP Address Group.
  1. Navigate to Configuration > Services
  2. Double-click on the SMTP service
  3. Click on the Access tab

If an IP Address Group has been selected then disable that option, apply the change and then ask the user to try sending another email.