>Either this is bullshit
> or you have a total of 10 users.
I have 171 users.
>Try running an ISP, even a small one with just a few hundred users, and watch how much bitching you have to deal with when you block ConstantContact, MailChimp, SendGrid, etc..
We get some rare/occasional bitching, and we explain why we do what we do, and they are then appreciative of our very low spam rate and find some work-around.
One can't do that as an ISP, since it is like censorship. But we are not an ISP and can do what we want. Most people *like* getting rid of all the marketing **** Email. Rarely it is an issue with some newsletter or whatnot that we can't get, and if it is important, the sender can send it directly from their own domain (and usually they are cooperative in such cases).
The reality is the reputation of a sender can be VERY tarnished by using a third-party mailing system. Not my problem. They are free to use a third-party, I am free to block those third-parties.