Vincent Lefevre asked,
| Some mailers don't add an In-Reply-To field with a msgid (nor a References
| field) when replying. Does anyone have written a recipe that automatically
| adds an In-Reply-To field? e.g. based on the first line of the body that
| generally is something like "On <date>, <user> wrote:"; the msgid of the
| original message could be retrieved from a cache.
I'm a little bit confused here.
Within the procmail-using universe, when we want to reply automatically to
an incoming letter, we use formail -rt (or, in some cases, formail -r), and
that will always include the Message-Id: of the arriving letter in both
References: and In-Reply-To:. We can get rid of those headers by going to
the additional step of adding "-I Reply-To:" or "-I References:" to formail's
command line, but if we don't do the extra work, they're there.
So, Vincent, I don't understand the situation where you need to add it
yourself. Are you trying to insert an In-Reply-To: header naming an old
message from you when you receive the reply to it?
If you're trying to figure out which of your old letters somebody is
answering, and you keep copies of the mail that you send, can't you look it
up by the text you wrote that is quoted in the reply or by the subject line
if it wasn't changed (beyond adding Re: if it wasn't already there)? If
there is no quoted text of yours in the response, how can you hope to find
something else in it that specifies which letter from you is being answered?
If you want to make sure you have those headers on your outgoing responses,
formail -r[t] puts them there. If you want to insert them into mail you
receive, I don't understand the value, and the task will often be impossible.