I know more about email transport and email clients than I do about text message transport and client software. Is Scoutbook sending text messages via email to a email/text message gateway?
A quick search of the internet and standards found:
Some mobile carriers have switched to transporting text messages as HTML attachments. (I believe HTML5 is now using UTF-8 characters. I suspect they may be converting SMS to MMS to do this.)
Internationalization of email and text messages (using UTF-8 instead of ASCII character sets) may be a factor. When internationalized email was introduced the conventional email transport system and/or client software was modified to include the internationalized email message as an attachment. Something similar may be happening with text messaging.
Sending text messages as MMS attachments allows longer messages to be sent. Sending text messages as HTML allows character formatting and perhaps other HTML features to be added.
a. Run the latest version of your cell phone software and keep it up to date.
b. My email client software allows me to specify that email from a certain email address be delivered only as text. Does your cell phone have a similar feature?
c. Can we determine if the same behavior is happening on different types of mobile devices? Different carriers?
If Scoutbook messaging is now internationalized I do not think it should be set to only send conventional text messages.
Of course, I could be completely wrong since I am not a text message technical expert. But the above are my guesses.
Gook luck with solving this one.