The following Bugs have been detected in Groupwise R2 so far.

Webmail search doesn't work. No results are returned using any setting folder or search pattern. Two totally independent systems show the same results.
Rules appear to be partly broken. [Contains] no longer works for parts of email addresses. We now have hundreds of emails not being processed by rules.
The Menu on Webmail doesn't scale properly. Some browsers only it seems. Cosmetic only.