I'm wondering if somebody else has experienced similar problem with ASA 5520. We have an e-mail server on inside and spam filter on outside. I have allowed smtp from spam server to e-mail server on inside and www from any outside to e-mail server on inside for OWA plus pop3. I was able to send e-mails, but not to receive. OWA connection was just timing out. It was possible to connect, but in a couple of second the connection was gone. I checked logs on ASA and I'm sure that issue is not the access list. Connection to another server on the same subnet was fine, so the problem wasn't routing either.
I got rid of esmtp inspection and got the same result. The server in question is performing badly, possibly this problem would not occur with a most of regular servers. I'm really curious what possible work around could be others than changing the server.
We have configured the outside and inside Interface with official ipv6 adresses, set a default route on outside Interface to our router, we also have definied a rule , which also gets hits, to permit tcp from inside Interface to any6.
In Syslog I also se...