I know v7.000 GA has been released, but I suspect that the following will be just as relevant.
I have tried various version of V7b on two basic types of hardware,
1/. AMD K8
2/. Intel Celeron
Both boxes ended up with 1gb of ram and used the same NIC, swapped between boxes.
I built the Celeron 1300a as a low power box and used a config from the AMD k8 v6.933 to restore it.
I found that the
1/. the POP3 proxy functioned differently
2/. the SMTP proxy functioned definitely
I configured the SMTP proxy to work without a local e-mail server, this functioned the way I wanted under the AMD box, but under the Intel box it started dropping (not delivering) e-mails because I was a home user going direct.
The SMTP proxy was and still is configured to use smarthost.
I have rebuilt the AMD box and used the same config to restore it and the SMTP proxy went back to working the way I expected it too.
There were other issues during setup of the Celeron that were just plain frustrating.
The DNS script took 5 attempts before it would work.
One of the mail functions took over an hour and many reboots to get working e.g. the box wouldn't pass any e-mail.
Ian M