That is exactly what I am doing. When people register on my sites, I have a pop up telling them to avoid using any email account has to do with Microsoft.
So far, no complains. I am waiting for the day Google kick them in their asses.

I realize that I could pay for a service to have my mail delivered to Hotmail and if that’s the solution then Microsoft needs to just broadcast that to the Web community and say “If you want mail delivered here, you have to pay for an approved 3rd party service. We’re sorry we have to resort to this but it’s the only way to effectively control SPAM”. You can explain *that* to a client. Explaining mystery mail that neither gets delivered nor bounces back doesn’t sit well with paying clients.

Google gets it right. My G-Mail is better than 99% SPAM free on the inbox, less than .1% legitimate mail in the junk folder and I have yet to have any mailed blocked from domains and clients I work with. I don’t even check the junk folder any more because of its accuracy.

At this point I have no choice but to tell people to convert to G-Mail and then send them an invite.

http://www.tamingthebeast.net/tools/anti-spam.htm

I guess one of the few disadvantages of it is the sender having to jump through a hoop to get their email through; but if it’s important enough, they will.. bit like double-opt-in subscriptions; if the subscriber really wants it, they’ll click the link in the confirmation email. I do see challenge/response being somewhat of an issue in a pre-sales scenario though.. that’s the time that we don’t want people having to jump through hoops. Still, there’s a way around everything.

Years ago I decided that anyone who uses spam filters doesn’t really understand what they are doing.

ISPs that use spam filters are engaging in what I would call unconscionable conduct.

Why?

OK, spam is a problem. Spammers can make life miserable for everyone.

BUT, an inappropriate response to spam is even worse.

We are now getting to the stage where email can no longer be used for business communication.

I’m not talking about mail outs. I’m talking one-to-one communications.

I’ve never used a spam filter because I am in business – I cannot afford for a prospect’s or customer’s email to get lost.

If spam filters worked – and by that I mean zero false positives (i.e. no legitimate email gets block) – they would be great.

But they don’t work!

Even though I don’t use spam filters, I don’t get spam.

Why?

Because I use challenge-response.

IMHO, challenge-response is the *only* valid way of stopping spam.

Spam filters are destructive.

Challenge-response is pretty much perfect.

Sure, each spam generates a challenge email. Sure, ISPs might not like that.

But ask yourself this….which is more expensive? A few more bytes across the internet or the wasting of people’s time.

If idiots like Hotmail continue with this stupid approach, I can see the day where email is just no longer used by anyone.

That’s one hell of a cost for all of us to pay!

This information was very timely, thank you.