🚀 go-pugleaf

> *Excerpts from ext.nn.comp.mail.sendmail: 26-Apr-89 Re: sendmail parsing*
> *questi.. Bruce G. Barnett@crdgw1. (446)*
> But most sendmail.cf files I have seen include something like:
>       R$*<$+>$*       $1$2$3
> It may be that the spec says angle brackets are required,
> but is that really the case?
Most sendmail.cf use the ``<>'' characters to bracket the name of the
destination machine, strictly as a means of making the string processing
possible.  This use of ``<>'' is totally independent of the use of ``<>'' in
surrounding source-routes.  (Check the crackaddr() routine for confirmation.)
When you see a rule such as you quote, you can be sure that the address being
manipulated isn't a full RFC822 address, but is the essential (rfc821) form.
Thus, even if the To: field of a message were
        To: Joe <@host1,@host2:joe@host3>
the text that would be sent to the rule above would be simply
        @host1,@host2:joe@host3
and the job of Sendmail's rule 3 is usually to turn that into
        <@host1>:@host2:joe@host3
so that rule 0 can look at the bracketed host name to figure out where to send
it.

None of this has anything to do with source-route brackets, which should be
being added back to the source-route (if it is a source-route) when actually
being put back into a header or used in an SMTP conversation.

                Craig