Responding vs. Reacting

Today I got an email at work that was just rude.  It wasn't directed at me personally, it was the reaction of a person who had been told no and didn't get their way.  So this person decided to spout off their frustration to a person they don't know (me) in the form of a rude email.  I wish that, at the time, I could have looked at this situation with the kind of reason and matter of factness (is that a word?) that I did in retelling the situation right now.  Unfortunately, my response was for my blood to boil and to get really upset.  It isn't fun to get any kind of communication that is addressed to you that then rips apart something you believe in or a policy that you've had to enforce. While I didn't stay upset about this for long, it certainly had a negative affect on me, the way I disrupted my coworkers by being upset about it, and on my husband since he was home and I had to tell him how I'd been wronged.
I think what can be dangerous for me in the way I respond is that there really isn't anything "wrong" with my reaction.  I don't write nasty emails back to the people blasting them for what they said to me.  I'm not rude in my responses to the person at all.  What I feel is wrong about the way I react is the way it changes my attitude, causes me to panic, and causes disruptions for the people in my life.
I don't want this to be my reaction.  I want to, in the moment, be able to be reasonable and not reactionary (like the sender).  I want to be able to brush these kind of things off so that they don't then go on to disrupt the way I do everything else in that day, hour, half an hour, etc and the way I interact with everyone around me that I care about in that day, hour, half an hour, etc.  Or I want to be able to give it time to sit so that I can reevaluate once I've had time to process.  It is my prayer that going forward I'll recognize rude for rude, respond professionally, and move on without letting those little things (and they are little) disrupt the peace.