dragonxi sorry, I just noticed that you said mail.de.opalstack.com, not smtp.de.opalstack.com (which is the subject of this forum post).
There have been no attacks on mail.de.opalstack.com.
The next time you notice this problem, please email Opalstack support (not a forum post) with the following info:
- The precise date and time (with time zone) that you noticed the problem.
- The name of the mail user that you are trying to set up as an account in your mail client.
- The public IP address of the system that you are running the mail client on (ie the address that you get at whatismyip.com)
- A screenshot of your mail settings
- A screenshot of the error message
Once you've emailed the info to support we'll look into it further.