On 7/1/2013 2:51 PM, Wietse Venema wrote: > Noel Jones: > [Setting the subject to "fax from 555-1212"] >> Since this isn't real email, it might be sufficient to always add a >> Subject header, even if one already exists. And maybe throw away >> the existing Subject too. >> >> I'm pretty sure postfix will only add one header, despite this rule >> matching multiple headers. If it does add multiple headers, you can >> try matching /^Message-ID: / or /^From: /, but those aren't required >> headers either and may not always be present (or just ignore the >> ugliness -- multiple identical Subject: headers probably won't break >> anything). > > It's easy enough to ignore existing Subject: lines, but adding > exactly one requires care. The bad news is that PREPEND action (in > access, header_checks, body_checks) will prepend text for each match. > > Adding text once robustly requires changes to Postfix, without > entering the slippery slope that ends with a Turing-complete language. > > Of all the alternatives that I could think of, EOH pseudo pattern, > match count options in the regexp/pcre implementation, the only > change that seems reasonably implementable is to apply header_checks > to an empty line to signal the end of the message header (which > means Postfix would have to supply this line when none exists). > > /^$/ PREPEND Subject: fax from 555-1212 > > Then, new safety code would have to be added so that REPLACE, IGNORE, > etc., won't remove an existing blank line from the input stream. > > Wietse >
Maybe a PREPENDONCE action that only fires once per message? At any rate, this new feature doesn't seem to be worth spending much time on. -- Noel Jones
