Texting a Short Code (123123) Phone Number from Email

i use to work at phone company and i don't understand what your taking about

Short answer - no. Needs to be done via proper sms gateway and they will want to reply and most short codes are after your phone number anyway.

How is this an r/msp question?

I've never heard this question before.

Even if you'll be able to send the message, you most likely won't get a reply back as you lack a proper phone number, and replying to emails is not what these systems have been designed for.