Limited space for mails or mails with subject "quota violation".
The mathematics mail server is also subject to restrictions, i.e. only limited space is available to each user with a benutzer@math.uni-paderborn.de mail address.
If the space is almost exhausted, you will receive mails with the subject "Quota violation". You then have 7 days to make room in your mailbox. This can be done on the one hand by deleting older mails, and on the other hand by increasing the available space. The latter can only be done on a case-by-case basis and by contacting an RBM employee.
You can view the memory usage of your mails via Horde, the browser email inbox. This can be found at https://webmail.math.uni-paderborn.de/horde/login.php. Once you are logged in, click on "Inbox" under the "Webmail" banner. Then you can see the memory usage at the top right.
Some clients, like Mozilla/Icedove are able to show the usage of your quota. The warning window is shown only from a memory usage of 75%, from 80% it is shown yellow and from 95% red.
In the webmailer the used space is displayed above the list of the inbox, if the space is running low it will also be highlighted.