Is the website sending spam text messages?

Every so often we get feedback from associations whose members think they are receiving unsolicited text messages from the website.  This article will explain what's happening and why somebody might think those messages are coming from the website.
First of all, and most importantly, those unsolicited text messages aren’t coming from their association's website.  They are coming from the “Email To Text” service provided by their wireless carrier – which is a free service that can be used by anyone.
The Email To Text service of the carrier will take an incoming email sent to the phone number’s email address, convert it to a text, and then send it as a text message to the handset.  When the handset receives the text message, it will always come from the same phone number – which is the phone number of the Email To Text service (and NOT the email address or phone number of the original sender).
We're able to test on the Telus network most often, so the texts always come from the number of 999-999-9999 in those cases, which is the Telus Email To Text service number.  If anyone in the world (including a spammer) knows the phone number of a Telus subscriber, they can send an email to [10-digit-number] and that person will get a text message from 999-999-9999 with the message.
We’ve investigated using a true SMS service for sending out the messages created by the sites, however, there’s a cost of at least $0.01 per text message in doing so.  While that may not sound like a lot, in our research most associations send anywhere from 5K-15K text messages per season and (from those who we've asked so far) nobody wants to pay hundreds / thousands for better text messages when the free Email To Text service works 99.99% of the time.
Long story short – those texts are spam that have nothing to do with the website.  Unfortunately those spammy texts would also probably have been sent / delivered regardless of being subscribed to the website.  The addresses to use for the Email To Text services of most providers is available publicly, so then it's just a matter of a spammer guessing the 10-digit phone number (which is easy).  Some wireless providers allow their customers to request that they disable the Email To Text service for their own handset – but of course if they do that then the text messages from the website won’t be delivered either.