Those webmail accounts are too anonymous, too "disposable" and too easy for evil spammers to create (check out how they use cheap labor just to beat captchas). So we always required that you use your "company" domain name. To be honest, we’ve always hated that requirement, because no matter how logical our reasoning was, people complained.
So we’re experimenting with something.
We just added SMS verification to our free trial form. If you signup there with an email address from one of the most popular webmail clients, you’ll be asked to enter your cell phone number & carrier.
We’ll send a code to your mobile device, and if you can verify it, we’ll know you’re a human (plus, we’ll have a "paper trail" for your account).