No hint yet, sorry.
But I can confirm the error running PHP 4.2.2.
I receive all extra headers in the mail body. Subject line is okay.
Plus, i get extra blank lines in the mail, that ez3 sends (CR+LF problem?). I'm using Eudora 5.2 on windows, which has no problem with linefeeds in any other mail.
Edit: I'm running a ezP 2.2.9 installation on the same server (PHP). The mails from there do not have any mail headers in the body... but i don't know, if ez2 sends any.