Due to a possible attack, the mail system was only partially available yesterday, June 19, from about 4:00 p.m to 23:00 p.m.
Currently, there are repeatedly short outages of the system and disruptions in the login.
If you have problems logging in, please try again only after 2 hours, so that your session ID can reset automatically.
No data (or e-mails) have been lost.
[Update 06/21]
The malfunction at Mail.UP was fixed on 20.06. around 17.00 a.m.