[exim] Sender verification and rewrite rules

Hi,

I need some help on a sender verification issue, that arises in
combination with recipient rewriting.

In short:

Envelope-to rewriting isn't done when performing sender verification, so
when an incoming message has a "local" sender, which would otherwise be
rewritten, rewriting does not take place, so routing -and therefore
verification- fails.

What should I do to make address verification succeed on addresses that
can only be routed after rewriting? See below for the things I have tried.

The only thing I can think of, that I haven't done yet, is to rewrite
the sender of the message using the same rule. Can this be done _only_
for verification? I'm not sure I want the sender address to be rewritten
when delivering mail.

The long version:

I had a rewrite rule like this:

*@* "${local_part}@${lookup mysql {MYSQL_REWRITE}{$value}{$domain}}" T

with MYSQL_REWRITE being:

SELECT todomain FROM rewrite WHERE fromdomain='${quote_mysql:$domain}'

..to rewrite the envelope-to on incoming messages. All quite simple, and
mail delivery works like a charm.

However, when an incoming message has a sender address, that is local to
my server and that would be rewritten by the rule above, sender
verification (from the RCPT ACL) fails. It appears that the address
isn't rewritten before the verification and during verification, the
original address is passed through routing, which fails.

Then I read in the spec (31.2):

"Similarly, at the start of an ACL for RCPT, the current recipient’s
address may have been rewritten by a special SMTP-time rewrite rule, but
no ordinary rewrite rules have yet been applied to it."

Clear, so I changed the rewrite rule to:

\N^(.*)@(.*)$\N "$1@${lookup mysql {MYSQL_REWRITE}{$value}{$2}}" TS

and the lookup query to:

SELECT todomain FROM rewrite WHERE fromdomain='${quote_mysql:$2}'

to make rewriting take place before the ACL is run, but that still
doesn't work.

Testing with 'exim -d -bvs' still shows it is trying to route the
unrewritten address, where 'exim -d -bt' shows rewriting is done on
delivery just fine.

I don't want to go down the road of sender address rewriting, if not
absolutely necessary. My gut tells me this shouldn't really be
necessary, but I'm kind of stuck here...

Thanks for any advice,
Martijn.