[exim] How to debug readsocket?

I have a few servers running Debian 7, with Exim. Each of them I have an
SRS daemon running.

>From Exim I use a router like this:

  address_data = ${readsocket{/tmp/srsd}\
                {FORWARD $sender_address_local_part@$sender_address_domain
ikcheck.com\n}\
                                        {5s}{\n}{:defer: SRS daemon
failure}}

Exim runs under the user mail and SRS also runs under the user mail

That has worked for years and life is good.

I have setup a new machine with Debian 8, life not so good.

I know the SRS is running fine, I can use socat and connect to the socket
/tmp/srsd and feed it the command it needs and get an answer back.

I can feed it a command like this: FORWARD test@??? ikcheck.com

It will return this: SRS0=f2kQ=PY=example.com=test@???

That's cool, that is what it is supposed to do.

Unfortunately on this Debian 8 box, Exim is not altering the envelope
address of the outgoing message.

I know it is running because I have it adding a header line to the outgoing
email, saying what it has done. It adds a header like this:

X-SRS: Sender address rewritten from <example@???> to <""@>

It should actually indicate the new SRS0 address.

My first guess would be permissions, but I don't know how to debug it. How
can I increase logging or somehow monitor what is hapening when it tries to
execute the readsocket command?



Robert G.