Zitat von mpca am 12. Mai 2021, 16:51 Uhr

https://webbanshee.net/remove-old-owa-versions/

When you need to upgrade a couple of servers one after another a server that already has been updated to the newest CU still needs the OWA version files from the last CU. If the mailbox which is being accessed through OWA resides on a server still running the old CU then an already upgraded server which serves OWA needs to be able to speak the old language as well.

According to this, I have moved all old OWA versions from /Owa/prem that did not have a match in /Owa and were older than 2 years to another drive. It gained me about 6GB free space.