[exim] Set DSN Options After Reception

Hi,

I want to turn on DSN success notices for mail after it’s received based on criteria like sender or the inclusion of a header. It would mean I could use DSN even when my client doesn’t have support for it. This was a thing with Sendmail, using the RRTImpliesDSN option which would synthesise DSN success where Return-Receipt-To was among the headers of incoming mail.

Can it be done, presently, without simply routing such mail through a proxy that re-injects it? I want to do other things too, like rewriting envelope and sender headers, and the more that I can do in Exim the better.

Cheers,
Sabahattin