Envelope sender address and KMail

Dear folks Does anybody know if there is a possibility to influence the choice of the envelope sender address in KMail? I googled a bit on this topic today and found out that KMail (and probably many other mail user agents) creates the envelope sender address according to the FROM address specified by the user. However, it would be a big benefit if one could specify the envelope and from addresses individually, especially when posting to mailinglists like this. I'm aware of, that one could configure the sending MTA to rewrite the mail headers, but I'm rahter looking for a solution on the MUA-level. Thanks for your suggestions! /Sven