May 26, 2018
Milter that adds mail header warnings on mail from open-relays
This is a simple sendmail milter which adds an X-RBL-Warning header to any emails that are received that come from an open relay as determined by your choice of RBL checking service i.e. bl.spamcop.net.
This is useful if you’d rather have the mail user agent MUA deal with potential spam rather than just blocking it in case you loose legitimate messages. Note that the X-RBL-Warning header is only set if the site was found to be an open-relay.