I think it's so easy to automatically get pissed off about things that seem huge at the time, but in the long run aren't that significant. Yeah, it's annoying and yes it's rude, but is it helpful to anyone for me to get upset?

What helps me is to always assume the best about another person. If someone hasn't responded to my e-mail in a timely fashion, I think "Maybe they're sick, or thier computer broke, or they're very busy and have a deadline they need to make..." Even if they're really is no good reason, my act of giving them one helps me to put it in perspective.

I would want someone else to assume the best about me, and it helps me not to be so upset at that moment. Usually I can just move on and forget about it until the issue resolves.