I don't know if I'm the only one who thinks this, but I do find it quite ridiculous for you to ban email adresses from Yahoo, hotmail, and GMail.
That is your opinion...
I know it's for security reasons, but I'm still not liking it though It still seems unfair.
If you know it's for security reasons then it:
1. Can't be rediculous as you first stated...
2. Can't be unfair ... as it's for everyone's security...
While it may seem unfair, it is due to the previous actions of others, who were in fact using 3rd party email hosts, that caused the decisions to put things the way they are. We don't appreciate hackers, and those that just log in to gain access to your information to spread spam and such. Thus we ask that we have your real e-mail address (from your ISP) so that should such things happen, we can get to the source of the problem much easier than having to deal with these 3rd party places that couldn't care less what their users do to places such as ours. By having to have an ISP e-mail we can report abuse of our system directly to that ISP and have it dealt with in an appropriate manor!