Good evening, @VaRoleplay ...
Adding a signature to the bottom of your messages via the Canvas Inbox is not possible at this time. It's a popular request, though. Here is an existing Feature Idea that's already been submitted that I would direct your attention towards: Signature Block - Canvas Community. If you feel that this Feature Idea aligns with something you'd like to see implemented by Instructure, then you might want to give it a star rating and also post a comment to that topic letting their engineers know why it would be important to you.
I know this probably isn't the answer you were looking for, but I hope it has helped to answer your question. Let Community members know if you have any other questions about this...thanks! Take care...be well.
