Replying to emails (in neomail) from other cpanel based serv

When a user receives an email from another cpanel based server, when you reply to that email (in Neomail) the To address becomes user@host.domain.com (ie: john@server3.host.com) instead of the real email address user@domain.com (ie: john@mylife.net).

Any idea how to fix this, whether on the receiving server or sending server?

[Edited on 11/21/01 by tabernack]