originated from but most e-mail clients discard custom headers but preserve a 'In-Reply-To' header with the original message-id.
Don't count on it! :) I spent quite some time working on a full-text mailing list search/archive system and one of the things I wanted to do was preserve thread informtion. However it was surprising the number of MUAs that did not generate a In-Reply-To header. Mostly it was Microsoft Mail Client and quite a few similar internal mail systems with internet gateways. Also beware that many mailers use the NNTP standard of References: instead of in-reply-to. I would suggest using the Subject line instead and generate some sort of ticket number and store it in the subject line, and put a header in the message body instructing the user to not alter the subject. -Matt -- Matt Hamilton matth@netsight.co.uk Netsight Internet Solutions, Ltd. Business Vision on the Internet http://www.netsight.co.uk +44 (0)117 9090901 Web Hosting | Web Design | Domain Names | Colocation | DB Integration