Helping people with computers... one answer at a time.
Typing email using all upper-case characters is the email form of shouting and is considered quite rude. Don't be surprised if you get a grumpy response.
WHY DOES IT SEEM LIKE EVERYONE I EMAIL OR INSTANT MESSAGE GETS ANGRY OR CURT WITH ME? DOES THE INTERNET JUST MAKE PEOPLE GRUMPY?
Well, computers and the internet certainly make people upset from time to time, but in this case, I'll bet that it's something much more specific.
In this case, it might just be you.
The "problem" might be that you're typing your message in all upper-case characters. That's typically read by others on the internet as shouting. Imagine you're having a conversation in a quiet room with someone who is shouting loudly for no apparent reason instead of talking normally. You'd get grumpy, too.
All caps as shouting has become deeply ingrained in net etiquette, or "netiquette". When reading text in all caps, many people internalize that as shouting without even thinking about it and react accordingly.
You may not be doing it on purpose, but I definitely suggest using all caps only for emphasis or when you're really trying to convey that you are, in fact, shouting.
RFC 1855 - Netiquette Guidelines has a good summary that includes this and many other things to keep in mind as you communicate on the internet.