1. Some people have a permanent chip embedded on their shoulders. I know that every league has one person or another who seems to be looking to be offended by something you've written. Be very careful when sending this person email! Of course, you're not going to be able to anticipate every imagined offense caused by your "insensitive" email, but you can probably head off quite a few disasters if you're especially careful about email sent to that one special snowflake.
2. Remember that email is never private. Email is the easiest thing to share, ever. Don't deny it...you can forward it easily and copy and paste it into a chat faster than you can say "NSA." If you don't want your opinion of certain people in your league or policies to become possible public knowledge, don't email it to someone. Hey, we've all done it, so I understand that it's not always avoidable, but send those bitchy emails with care. You never know when they're going to come back and bite you in the electronic hiney.
3. Don't use all caps. YOU ARE YELLING WHEN YOU USE ALL CAPS. Enough said about that, right? Seriously, all caps are just like someone yelling in my ear when I see them in an email. Don't be that league member.
4. Your tone can't be "heard" in an email. Unlike all caps in an email, tone is really really hard to convey in an email. Sometimes you can say something that can be taken several different ways, and of course most people will take it in the worst way ever.
5. Spell check that mofo. Spelling counts, typos count, fixing typos count and resending another email to correct your mistakes just makes the whole event less serious. You lose a lot of gravitas when you have to send another email to fix a typo or a wrong word. I should know, my phone likes to substitute all sorts of wonderful words when I'm not looking. (Bad phone! Of course it isn't me typing that wrong word. Damned homophones.)
6. Reply no matter what. People don't necessarily want an immediate answer, but if you never answer an email, people either feel ignored, or worried that the email got lost in a spam filter. Be kind, you should especially be kind to your league mates since they have the ability to slam you on the track on a pretty regular basis.
7. Think before you send it. Do you really think you should send this email? Did you read it carefully? Did you answer out of anger and disgust? If so, hold on to that email and WAIT (yes I was shouting) a couple of hours to send it before you make a misstep. Sometimes you don't need to IMMEDIATELY answer every email.
8. Remember not to be offended by email you get. Yes, we've all gotten that occasional email that hurts our "feeling." Take a deep breath and read that email again. Was your league-mate trying to be a dick? Probably not. Try to stifle that butthurt before it blossoms into BUTTHURT GIGANTE!
Always avoid the Butthurt Gigante.