@Scott Earle

"But there are people like him working at larger companies whose job it is to provide an email service (incoming and outgoing)."

True, but I'd argue that part of providing that service - presumably a large part of a mail admin's job - is deciding what to allow into the networks that they administer. It's their choice, or it's the policy of the company where they work - either way if they choose not to accept mail from certain IP ranges, or which contains the word "aardvark", or on Tuesdays, then that's up to them. Of course if this means that they lose some mail they might otherwise have wanted, then they only have themselves to blame :-)

Once an admin has made that decision, and you find yourself on the wrong side of it, then your options are either send in a manner that they do accept, or ask them to poke a hole in whichever rule you're falling foul of, or live with it. My point was that taking that decision in the first place doesn't necessarily make the admin a pillock :-)