You may have blocked all msgs comming from e-mail addresses. Which can be set/changed at www.vtext.com. when you login with your my verizon user/pass then click on preferances then txt blocking.

if you are trying to send a msg from your e-mail to the phone it would be (your number)@vtext.com. sending to your e-mail would be normal just enter the email address in the recipient field. If you get any errors check your account features to make sure that you dont have the premium txt block