Craig Kelley wrote:
> I would like to uniquely tag a message after it's been "seen" by a
> transport. I was thinking of something like this:
>
> headers_add = X-Done-Spamcheck: ${md5:thisisthespamsecret$h_Message-ID:}
>
> Where "thisisthespamsecret" would be the "secret" and the Message-ID
> would be the unique bit of information in an email. I'm worried that
> Message-ID may be null at some point though? Is there a better string
> expansion to use as some sort of unique identifier?
IIRC Message-ID is ALWAYS available when running the transports, either
the original one or one generate by exim (when there was no msg-id while
receiving the message).
Btw, you should consider using the hmac expansion item instead of md5 on
it's own, see
http://www.exim.org/exim-html-4.30/doc/html/spec_11.html#IX795
Nico
