Header Checks: PREPEND

Hi guys, So, I'm trying to use PREPEND to add in a custom header so that support can easily track what email address was used in RCPT TO. I've tried the following: main.cf: smtpd_data_restrictions = check_recipient_access regexp:/etc/postfix/header-checks header-checks /^(.*)/ PREPEND X-S

smtpd_command_filter regex help

So, I'm having an issue with "Bad Sender Address Syntax" errors. The errors are from a variety of formatted email address including some strange ones like . At first, I would shrug my shoulders to them but my customers started whining and they sort of had a good point. You see, all of the ema