I agree with Shaun--it's too easy to misintrepret an email, imo. Plus, I think that a lot of times, we just write stuff and don't bother to think about how it comes across to the other person...until after we hit "send" (when it's too late!).
Sometimes, if I'm really frustrated, I'll "write" an email, with no sender in the "sender" box and just write what I feel. Then I let it sit for a while (an hour maybe?) and reread it. Usually, rereading it helps me realize that most of it is just me having a bad day or whatever, but sometimes, I'll reread and realize that this is something that I can't let go. ...
If I can't let it go, then I go to the next step, which is write up my thoughts feelings, and what I'd like to have happen. Just a short list (notes, mostly).
Then, when DH & I are sitting at dinner, I say, "There something I'd like to talk to you about if you have a few minutes, either now or later tonight." I make sure to pick times when he's not upset/stressed, and I'm not upset/stressed, and when we aren't distracted by the kids, dogs, etc.
Then, I use my notes for reference if I need to, and use "I" statements to tell him what's going on. Then ask him for his input, or let him know what I think might work to fix the problem. Or, depending on what it is, I might just tell him, and then ask him to hug me or sit with me for a few minutes & snuggle, etc. After we're done talking, I tell him I appreciate him listening, and that I love him. (this is of course the ideal, but I'm a big believer that aiming for the ideal helps, even if it doesn't turn out this way).
Example: I'm angry because the house is a mess and the dishes are stacked to the ceiling, and clean laundry that was in a basket in the living room is now strewn on the floor by the toddler, etc. So, I write out an email to vent (but DONT send it!!!!). Then I reread it and realize, that what I really am feeling is: Stressed out and like I need more help. So, instead of writing a nasty email, I write a list of what I'm stressed about, and then things that could be done. Then I sit down with DH and tell him, "you may have noticed, but I'm feeling kind of stressed lately, with the house being such a mess. Would you mind helping me with it? It would be great if you could do a load of dishes tomorrow and put away the laundry."
It doesn't always work out, of course, but it's always worth trying. I find that if I'm really upset/emotional, it doesn't usually go as well, and there are definitely times I have to leave the room and come back to it later, if I'm upset. Fortunately, DH is a very laid-back person and handles it really well (he's just sort of oblivious to the house being a disaster, LOL).