I am running Debian GNU/Linux on an i386 system. I had difficulty with mail delivery to one address because Exim4 was using the username rather than the mailaccountname in mail addresses. The "Return-Path:" and "envelope-from:" headers read "[EMAIL PROTECTED]" rather than "[EMAIL PROTECTED]". - However, the "From:" header (which is set by Mutt) read correctly "[EMAIL PROTECTED]".
The solution was to add a one-line entry to the file "/etc/email-addresses": rlh: [EMAIL PROTECTED] In other words: username: [EMAIL PROTECTED] RLH