[exim] Explanation of the working of verify = sender

As I said in earlier postings, all e-mail arriving from the Internet is
virus checked by our company mail relay server before it is forwarded to
our local MTA (Exim 4.63).

Since becoming the postmaster of our local MTA several months ago I have
managed to add extra checks into Exim's config file with the help of you
Exim experts so that a lot of spam is now removed.

A final sender verify check in the acl_smtp_rcpt ACL is causing me some
problems.

My query is the working of the following:

        warn    hosts           =       +company_relays
                logwrite        =       Checking the sender address
'$sender_address'.
#               !verify         =       sender
                !verify         =       sender/callout
                logwrite        =       Checking the sender address
'$sender_address'.

The verify always succeeds, both using sender and sender/callout, with
the first logwrite being written but the second logwrite is never
reached. Some of the e-mail addresses that are being verified look very
dubious and I am surprised they pass.


Is the verify of sender always succeeding because its SMTP session is
with our company mail relay server?


Thanks


Paul McIlfatrick