535 Incorrect authentication data / authentication required

[urbee]

I'm having problems with emails being sent out of outlook and other e-mail clients.

For a while everything was working OK, then all of a sudden people started getting "550 authentication required" errors and "535 Incorrect authentication data" errors (in exim rejectlogs).

Whats interesting is that da-popb4smtp is running on the server and that the config was not changed.

After i tried enabling "my smtp server requires authentication" it works but anyway, i want to know what happened and why doesnt it work without it?

 

[mr.applesauce]

Is pop before smtp even used anymore?

SMTP auth is almost always required now days to prevent spam.

 

[urbee]

As i said, i would like to understand why this even happened.