There are many different ways to deal with email overload.  I've been know to sort by person or by subject trying to figure out which ones need immediate attention. When I'm the sender, I try to use as descriptive a title as possible to help the recipient decide whether to open my message. Seth Godin has a 36 item checklist that he's recommends using before you hit the send button. Some of the things on his list are unique to entrepreneurs or marketing folks so I've reduced the list and taken some editorial license with the ones that I've outlined below. 

• Who is the email going to? If they didn't receive it, would they complain about not getting it? If they wouldn't complain, take them off of the list.
• Am I angry? If so, save as a draft and come back to it an hour later.
• Would it be better to discuss this subject in a phone call or face to face meeting?
• Am I blind copying my boss? If so, how will the recipient feel if they find out?
• Is there anything in this email that I don't want the media, the lawyers or my boss to find out? If there is, hit 'delete'!
• Is any portion of my message in all capital letters or colored red? If so, consider changing.
• Is my contact info at the bottom of the note? If not, add it.
• Could this email be shorter? If so, edit it.
• Have I attached a really large file? If so, consider an alternative way to provide access to it.
• Am I forwarding something about a virus or worldwide charity or anything that could be a hoax? Check the Snopes web site before sending
• Did I hit 'reply all'? Does everyone need to see my response?
• Am I quoting a portion of the original email that helps in understanding? Just responding 'yes' isn't helpful.
• If I had to pay 42cents to send this email, would it be worth it?

Taking a little extra time to think about the effect of your email on the recipient will go a long way to keeping your messages out of the trash folder. For some tips on clearing your own email in-basket, see my post here.