MMDF expects addresses to conform to the RFC 822 mail standard, available from the Network Information Center at SRI International. MMDF also supports RFC 733-style addresses for compatibility with earlier mail systems.
In addition to those in RFC 822, the following address
delimiters are recognized within the local part of addresses
(in order of precedence):
@ % !
The ``!'' delimiter is interpreted as ``host!user'' while the others are interpreted as ``user?host''. The following table shows examples.