SMTP error from remote mail server


I suddenly can’t send emails today and keep on getting errors as below. But, I have not changed any settings on my eM Client and my server.

There are the Errors shown in the returned email:
host com [ip]
SMTP error from remote mail server after RCPT TO:<name@gmail. com>:
550-Please turn on SMTP Authentication in your mail client.
550-webserver [ip]:58452 is not permitted to relay
550 through this server without authentication.

My eM Client Version: 9.2.1222
working on the MAC Apple Silicon version

Does anyone know what to do? Thank you.

Gmail accounts can no longer use username/passwords for authentication.

You will need to remove the account and then add it back again following the instructions here.