The best replacement for e-mail is email.

The best alternatives to e-mail are rated as following:
★★★★★  email
★★★  snail mail
★★  letters
★★  telephone
★  face to face communication
★  face to face
★  voice mail
  text messaging
  electronic mail
  postal mail
  instant messaging
  address
  im
  face to face meetings
  e-mail
  letter writing

Your alternative for e-mail is not listed? Suggest!
Speaking about e-mail, one probably shouldn't forget about attachments.

Other search terms related to e-mail and their ratings are:
★★★★★ attachments
★★★ attachment
You have in mind a companion for e-mail and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of e-mail in all years. Click on graph for more.
e-mail
email
snail mail