The best replacement for 365 is google apps.

The best alternatives to 365 are rated as following:
★★★★★  google apps
★★★★★  google
★★★★★  2013
★★★★  office 2013
★★★★  360
★★★★  google docs
★★★  360 interest
★★  360 days
★★  office
★★  office 2010
★★  hosted exchange
★★  2010
★  exchange
★  364 days
★  skydrive
★  office 2011
★  bpos
★  apps
★  exchange 2010
★  on premise
★  sharepoint
★  357xp
  microsoft office 2013
  366
  google drive
  office 2011 for mac
  gmail
  outlook.com
  windows live
  ms361
  sharepoint 2010
  office 2007
  exchange online
  exchange server
  live@edu

Your alternative for 365 is not listed? Suggest!
Speaking about 365, one probably shouldn't forget about outlook 2003.

Other search terms related to 365 and their ratings are:
★★★★★ outlook 2003
★★★★ sharepoint
★★★★ exchange
★★★ active directory
★★★ adfs
★★ outlook
★ sharepoint 2013
★ autodiscover
★ outlook 2007
★ lync
★ tls
skydrive
visio
outlook 2010
mac mail
access
office 2013
You have in mind a companion for 365 and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of 365 in all years. Click on graph for more.
365
google apps
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