[nos-bbs] cases of B2F showing up in BPQ sid ...

[M Langelaar]

I have put in a small mod for people to `try` out if this applies to you.

under rsync, just retrieve the one file, mboxmail_4GUS.c

I was told BPQ is giving out B2F in recent versions when you connect
to it, which to be honest JNOS has not been tested with. I only wrote
the B2F support for Winlink CMS systems at the time.

Forwarding with BPQ will get majorly messed up or something will simply
go wrong if we say to BPQ that we support B2F.

This `mod` will make sure JNOS only returns B2F for Winlink CMS systems
and will downgrade the forwarding session to B1F for any other systems that
are asking for B2F (for now anyways).

In theory the mod should work.

Maiko / VE4KLM