Hi there, @garthguibord.
Thanks for following along with the thread and sharing your concerns.
It sounds like you may have some browser issues going on. Such as corrupted cache. Web browsers collect cache to save time when loading repetitive data and images. Over time, these files can become outdated and corrupted, causing issues like the one with your error message. I've included the links for all supported browsers that contain the steps to clear the cache below.
After clearing cache, make sure to restart your browser. Then, try sending the email again.
Let me know how it goes and if you have any questions or concerns. Take care!
