Confusion with Allow Filenames

[Max Kipness]

I've been trying to find the answers from archived posts, but I'm still
not sure if the following should work or not. I definitely doesn't based
on emails with .bmp files attached sent from other mail servers (that
don't block .bmp on  outbound mail).

In mailscanner.conf:
Allow Filenames = /etc/MailScanner/rules/allow.filename.conf
Allow Filetypes = /etc/MailScanner/rules/allow.filename.conf

In /etc/MailScanner/rules/allow.filename.conf:
FromOrTo:       myemailaddress at domain.com        \.bmp
FromOrTo:       default

There are no errors being produced in the maillog, but the rule is being
ignored completely.

I saw another reference to creating the allow.filename.conf back to
individual filename.rule.conf files per domain, but I'd rather not do it
that way unless necessary.

Can the above work? Or what am I doing wrong?

Thanks,
Max