The "vast majority"??? Maybe of what you use, but the "vast majority" of the hundreds of thousands or even millions that exist that you have used?
How many SMTP providers do you use
? One per mail system is the norm
, and if you are meaning customers' systems you have set up then no doubt you tend to use just a few servers.
Server to server I would accept, but that is not what the consumer uses. They just have a mail client to a single server.
Kindness isn't going to cure the world of all its awfulness but it's a good place to begin. Daisy Ridley.
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