🚀 go-pugleaf

> From: Jerry Sweet <mailmod@ICS.UCI.EDU>

> I noticed a paragraph in a recent "NETWORK WORLD" ( September 3, 1990),
> which stated "The 1984 version (X.400), however, didn't provide a workable
> mechanism for remote US access to an MTA ("X.400 standards only need
> ncrowning touch," NW, June 12 1989)."

> Does this imply that I must have an MTA on each user platform ( say like
> PC's ) barring some sort of mail gateway existing on the MTA platform.

> I realize that this problem is repaired with the 88 version.

They are probably thinking of the P3 and the P7 protocol.

The P3 protocol is a protocol where the MTA more or less
automatically downloads all new messages to the UA.

In the P7 protocol, new messages are stored in a database,
from which the UA has some control on in which order to
download new messages.

The 1984 version of X.400 only had P3, while the 1988 version
also has P7.

I know that many people claim that the P3 protocol does not
work, but I do not understand why. Perhaps because P3 works best
if the UA is able to handle parallel processes (for downloading
and for doing other things at the same time) and most personal
computer operating systems are not so good at this. But if the
UA is implemented in a computer which can handle parallel processes,
like a Unix workstation or a minicomputer, P3 seems to be a very
reasonable protocol. But unless the connection between the UA
and the MTA is very fast, also P7 would work best if parallel
processes are possible in the UA computer, so that the user does
not have to sit waiting while messages are downloaded.

Many existing X.400 implementations do not support P3. But the main
reason for this is not that P3 is unworkable, but that these systems
integrate several UA-s and one MTA in one system, with proprietary
protocols between the UA-s and the MTA, and use X.400 only for
connection with other mail systems.