SMTP vs. dots

[zemon at felix.UUCP]

I started playing with the sendmail stuff which came with
4.3 BSD and had a user point out a rude surprise.  He tried
sending something like this

    To: felix!zemon
    -------
    foo
    .
    bar

and received

    To: felix!zemon
    From: fritz!someone
    --------
    foo

The SMTP protocol seems to have ended the message at the
dot and ignored the rest.

I'm using the lanroot.mc and lanleaf.mc configuration files
in the no-named directory.  The message originated at a
leaf site and was sent to the root site (felix), where
"zemon" is aliased to "zemon at fritz".  Using the MH send
command with the verbose and watch options, you see that
sendmail sets up a SMTP connection and the receiver says
that the message text should be sent with the end indicated
by a line with a single period on it.  Well, the receiver
keeps his word and ignores the rest of the message.  This
is probably a bug given the following....

Now the strangeness.  Sending the same message from kelly,
another leaf site, to fritz using the address "zemon at fritz"
instead of "fritz!zemon" works correctly.  But sending it
from kelly using address "zemon at felix" also fails by the
time the message is finally delivered to fritz.

So what's going on?  Is this a bug in the protocol?  Has
this been solved?  Shouldn't these things be escaped like
"From" lines?  Or something?
-- 
	-- Art Zemon
	   FileNet Corporation
	   Costa Mesa, California
	   ...! {decvax, ihnp4, ucbvax} !trwrb!felix!zemon