I have a problem with sending authenticated e-mails via SMTP on my hosting with CPanel using Exim.
The problem occurs only when the script send (connection) is performed internally on the server. When I run the same script in an external environment sending will be runs smoothly.
SMTP -> get_lines(): $data is "535 Incorrect authentication data "
I believe the problem is some configuration of WHM / Exim, because until last week was working, but some settings were changed to prevent automated spam submissions.
I do not know which settings are relevant to the solution of the problem. If you need to enter any parameters of WHM setup, just tell me.