Vanilla qmail 1.03 stores the envelope sender address (preceded by an F and followed by a NUL) in a file in the directory /var/qmail/info/. RFC 1869 ("SMTP Service Extensions") allows one to pass additional information on the MAIL command line after the FROM:<address> . Some of this information should in principle be passed on to qmail-local and/or qmail-remote for correct processing. (One example is BODY=8BITMIME. Regardless of how one thinks qmail-remote should behave when relaying to a server that doesn't advertise 8BITMIME --- I don't wish to revive *that* discussion --- it may be nice to pass on the 8BITMIME flag to those servers that do claim to support it --- but only if it was set on the inbound message; qmail-remote shouldn't try to compute it from the message content.) In the INTERNALS file, DJB wrote inter alia: Currently info/457 serves two purposes: first, it records the envelope sender; second, its modification time is used to decide when a message has been in the queue too long. In the future info/457 may store more information. Any non-backwards-compatible changes will be identified by version numbers. I think I may have a need to store more information. I would like to do so in a manner that won't clash with future official qmail releases. Would it be OK to store the information after the F...\0 envelope sender, as a (possibly empty) list of P...\0 parameters? Or am I better off creating a separate file xinfo/457 ? Sergio Gelato