[exim] Any trouble with check_string when appending to files…

Hello,

the appendfile router allows to change the check_string value for sites
that require odd postmarks. I read a pretty old discussion regarding
the format of postmarks that resulted in the fact that there are a bunch
different postmark formats in use and it makes most sense just to match
"From .*" (that is, From, a space and then just something not empty)
at the beginning of the file or after an empty line and to forget about
matching the data following it. Btw: The Exim specification says nothing
about the empty line.

Is there anybody, aside from MMDF users, who had to change the postmark
in Exim? I am also curious if anybody ever had a problem with postmark
matching in clients, should that be the case. This Exim feature is
pretty old by now and I am curious if it proved to be useful to anybody.

Michael