The best replacement for reply is response.

The best alternatives to reply are rated as following:
★★★★★  response
★★★★  reply all
★★★  retweet
★★  respond
★★  answer
★  reply to
★  revert
★  reply back
  reply to all
  replay
  out of office
  forward emails
  publish subscribe
  regarding
  prompt response

Your alternative for reply is not listed? Suggest!
Speaking about reply, one probably shouldn't forget about attachment iphone.

Other search terms related to reply and their ratings are:
★★★★★ attachment iphone
★★★★★ original message
You have in mind a companion for reply and it is not yet here? Propose!



Google Trends

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reply
response
reply all