I have just installed my new BT-445C and I am occasionally getting
this message.

charon /netbsd: bt0: mbi at 0xf86779e4 should be found, stat=81..resync

A missing mailbox--is it serious?

I am using:

NetBSD charon 1.0 NetBSD 1.0 (SORTOF) #1: Wed Jan 18 22:22:02 EST 1995
ken@charon:/usr/src/sys/arch/i386/compile/SORTOF i386

It is lightly hacked 1.0 (sort of).

Jan 19 20:49:28 charon /netbsd: bt0 at isa0 port 0x330-0x333 irq 11: version 4.2, sync, parity, 32 mbxs
Jan 19 20:49:28 charon /netbsd: bt0 targ 1: sync, offset 15, period 200nsec
Jan 19 20:49:28 charon /netbsd: bt0 targ 2: sync, offset 15, period 200nsec
Jan 19 20:49:29 charon /netbsd: scsibus0 at bt0