[exim] Alligate Gateway Does Not Like BATV Signatures

On the heals of the "Strange Sender Verification behaviour" thread where
it turned out that Alligate's software doesn't respond to the RSET
command correctly. It also seems that it refuses to accept any envelope
senders that contain a '/' (slash) character. So BATV signed messages
get rejected outright.

I've submitted the support form on Alligate's website with the relevant
information along with links to examples of BATV signed addresses.

I figured I'd just let everyone else here know. If you see messages
bouncing with "553 Unacceptable MAIL FROM address", this is the cause.

-Chris