This guide helps to resolve a mail error of type '535 5.7.0 authentication failed'

Resolve an Authentication failed error

The mail authentication service on the servers may encounter an issue for a few brief seconds exceptionally, for example during unusual events on the infrastructure.

If an error 535 5.7.0 authentication failed occurs:

• Try sending the email message again and it should go through.

If the problem persists, check the points of this other guide.