PMDF System Manager's Guide

The Grey Book protocol suite uses address formats that are similar to RFC 822, except that domains are specified in the opposite order; e.g., user@relay.cs.net becomes user@net.cs.relay.

PMDF provides support for this format on a per-channel basis. If the keyword grey is specified in the channel block, then all addresses in both the header and the envelope of any message queued to the channel will be written in Grey Book format. This facility is disabled by default. (The nogrey keyword is the default, meaning that normal address format is used.)

Grey Book mail systems typically do not use RFC 822 source routes but use the RFC 733 percent-style routing addresses instead, so the 733 and header_733 keywords are usually specified in addition to the grey keyword.

Note that the transformation is performed as messages enter and leave the channel; the rest of PMDF (in particular the PMDF configuration and alias files) always use the conventions of RFC 822.