Good luck trying to get everyone to use these or any other terms, in
exactly the way you want them to use them, on any particular occasion.
The people I know don't have any trouble understanding that the same system, and
sometimes the same program, is an MSA when it's talking to an internal
client, and an MTA when it's talking to another MTA found using an MX.
You might want to reread RFC 5598 so you use the terms consistently
with the way everyone else does.
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