[exim] submission+auth+sender

This is about exim 4.42.

On page page 319, 44.14, the Exim manual describes how a Sender:
header line is constructed under certain conditions. I sometimes have
the following situation:
Submission mode is on (control=submission) and the client
authenticates itself ($authenticated_id is nonempty).
A Sender: line of the form $authenticated_id@$qualify_domain is
generated and tested against the From: line.
Unfortunately, in our case the $authenticated_id is not a simple
username, but is a fully qualified address, i.e. username@domain.
Exim now adds Sender: "username@domain"@domain, which is pretty
ugly.
My wish for the wishlist: When the Sender: header is constructed,
it should be tested if $authenticated_id is a fully qualified address
or not. If so, $qualify_domain should not be appended.

Peter Rindfuss