The best replacement for google mail is gmail.

The best alternatives to google mail are rated as following:
★★★★★  gmail
★★★★★  yahoo mail
★★★★  exchange
★★★★  outlook
★★  hotmail
★  apple mail
★  yahoo
  microsoft exchange
  exchange server
  exchange 2010

Your alternative for google mail is not listed? Suggest!
Speaking about google mail, one probably shouldn't forget about my domain.

Other search terms related to google mail and their ratings are:
★★★★★ my domain
You have in mind a companion for google mail and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of google mail in all years. Click on graph for more.
google mail
gmail
yahoo mail