Can I add a custom header to mail sent from IMP?
To add custom SMTP headers to mail sent from IMP, place the headers in /horde/imp/config/header.txt. Make sure that your header is the last line in the file! You can include PHP variables by enclosing them in percent signs (“%”). One useful header is X-Originating-IP: %REMOTE_ADDR% which follows a de-facto standard adhered to by Hotmail, Yahoo Mail, and Dejanews (to name but a few) of listing the address of the computer at which the mail message was composed. Note that these are email headers, not body text. If you want to add an advertisement for your webmail service, or a similar announcement, to outgoing mail, put it at the bottom of the message (which is the standard location) by placing the text in /horde/imp/config/tailer.txt.
