I've got a bit of a problem on one of our web servers that also runs Zimbra as its MTA. By default, sendmail (or something buried deep within the server) adds a Return-Path header of the current user to any email sent out using the PHP mail command - for example, if Apache is running under the user apache, the return path becomes firstname.lastname@example.org
Of course, this behaviour affects reply processing etc. We use to be able to override this by setting the Return-Path header explicitly in the php code:
mail("email@example.com", "Subject", "Message Text", "From: firstname.lastname@example.org\r\nReply-To: email@example.com");
however this no longer works, and the Reply-To header is still set to firstname.lastname@example.org
Has anyone else had this problem and fixed it? The problem seems peculiar to this one server running Zimbra.