sendmail program

[Ruey Chen]

  We have a sophisticated mail program runing on Unix 4.2, we would like 
to port our mail program to the NCR Tower micro (Unix System V).
We can either convert the 4.2's "sendmail" to System V or use BRL's MMDF II.
Can any one out there give us some suggestion which approach is better.
We are familiar with the "sendmail" program not the MMDF program. 
We are primarily a DDN user.

  Does MMDF II available on the following system?  System V, System III,
Apple Lisa's Unisoft, Xenix(III) and Xenix(V).

  Can someone send me a copy of the user's manual of MMDF II?