For sending text messages that is correct. It may not be clear enough that the purpose of e-mailing a [NUMBER]@thinbox.com address is not to send an SMS to som

For sending text messages that is correct. It may not be clear enough that the purpose of e-mailing a [NUMBER]@thinbox.com address is not to send an SMS to someone's phone. The initial SMS is just a way to ASK for the recipient's e-mail address and create a mapping that works for future e-mails. So essentially it just couples two separate types of "addresses" for a person into a single address.