This isn't exactly what you're looking for but it used to be (long long ago) that T-Mobile had something called "Text E-Mail Services".(?) This was a webpage where you could customize your text-to-email experience. You could tell it to discard all e-mails addressed to your firstname.lastname@example.org. Assign your phone an e-mail alias (e.g. email@example.com) and assign short aliases to your frequently used outbound contacts. This was back before GPRS when you otherwise had to have a separate data line to use e-mail on a phone. They discontinued the service a long time ago. It didn't impact pure text messages, just the text-to-email service.
I don't know of any way to whitelist text addresses on an account-by-account basis. It seems to be handled on a network-wide basis.