Why am I getting an "Invalid Mailprotector Sender" bounceback?

When sending emails outbound, users can get a bounceback that states:
550 5.7.1 Invalid Mailprotector sender. *USER'S EMAIL ADDRESS*

There are two primary reasons that this bounceback happens:

1. The user is sending through Mailprotector's outbound relay, but they aren't a user in the Mailprotector console.
2. The user is sending to another user that has their domain in Mailprotector's console, but the user they're sending to isn't a user in the console.
   EX: User@domain1.com sends an email to DemoUser@exampledomain.com. "Exampledomain.com" is a valid domain in the Mailprotector console, but "DemoUser" isn't a valid user in the console. This will cause an "Invalid Mailprotector sender" bounceback even though the sender, User@domain1.com, is set up correctly.

How do I resolve scenario #2?

Contact Mailprotector via "Submit a Request." We will contact "exampledomain.com" and have the domain cleaned up.

How do I resolve scenario #1?

Go to the console and have the user added to the user list. You can do this manually or by setting up user sync.