
1) American invention
Found on
https://www.crosswordclues.com/clue/imail

Invisible mail, also referred to as iMail, i-mail or Bote mail, is a method of exchanging digital messages from an author to one or more recipients in a secure and untraceable way. It is an open protocol and its java implementation (I2P-Bote) is free and open source software, licensed under the GPLv3. As with email, one can send and receive iMails...
Found on
http://en.wikipedia.org/wiki/IMail
No exact match found.