The best replacement for groupwise is exchange.

The best alternatives to groupwise are rated as following:
★★★★★  exchange
★★★★  outlook
★★  lotus notes
★★  exchange 2010
★★  outlook 2007
★  microsoft exchange
★  zimbra
★  outlook 2010
  exchange 2003
  netmail
  microsoft outlook

Your alternative for groupwise is not listed? Suggest!
Speaking about groupwise, one probably shouldn't forget about outlook client.

Other search terms related to groupwise and their ratings are:
★★★★★ outlook client
★ novell
You have in mind a companion for groupwise and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of groupwise in all years. Click on graph for more.
groupwise
exchange
outlook