Hi @grashar1 ,
Welcome to the community!
We did an article that you may find helpful, this will guide you on how to fix getting SMTP authentication error please see the link below.
You may also try this article below.
Let us know how it will go.
Hi, I am currently using complete mail and everything was fine but am now getting 5.7.1 saying it is spam....... I can send through tpg mail