SMTP from behind hotspot problem

RouterOS The User Manager
1

Have a problem with clients sending email from behind hotspot. When they send, they get a error mail back from themselves saying ‘access denied’. Does not look like a usual failure message from our mail server. SMTP server is set in hotspot and even the same valid SMTP set in email client. No go.
ROS 3.20 on an RB411

Thanks
Ekkas

2

Seems like client had some other problems and explained the symptoms incorrectly. No problem.