I seriously don't understand why some people still insist on uppercase in sms or emails. Seriously???? That's equivalent to shouting, dorks.
Then there are some that like to use exclamation mark even in simple replies such as Thank You or OK. Seriously??? That's like telling people you are saying thank you for the sake of saying those words.
Thank You is a word used for showing gratitude. It doesn't have to be accompanied by an exclamation mark. Surely you don't verbally thank someone with a sarcastic tone. That is exactly how an exclamation mark sounds like in emails, you dork stupid people. That is just pure rudeness.
For God's sake, learn some proper manners when texting or sending emails.