smtp auth [e.g. sasl] support in the smtp/lmtp client

[btb]

hi-

is there support for smtp auth in the smtp/lmtp client?  my looking so
far in the documentation/source seems to indicate the answer is no.  if
not, might this be considered as a feature for a future release?

our specific use case revolves primarily around $notify_method.  our
architecture is as follows:

internet -> postfix -> [lmtp] -> amavis -> [lmtp] -> mda.

$forward_method and $release_method both pass mail directly to the mda.
however, i'd like to configure $notify_method to submit these
notification messages to our systems mail submission server [e.g. msa],
just as all of our other systems do.  for us, this means using smtp
auth.  without smtp auth, i'll have to make an exception on the msa, to
allow unauthenticated submission, authorized based on source ip address.
 this "works", of course, but i'd rather use smtp auth.

alternatively, could $notify_method be configured to use
/usr/sbin/sendmail?  if so, i could then use a null client, configured
for the amavis user, to achieve the same end result [although direct
support within amavis would be my preference].

-ben