Guild Mail
Then your mail box can get cluttered with guild mail. What if it was like a Message of the Day and would appear in your text box when you enter game/represent guild?
I think it is a fine idea. I have a hard time imagining your mailbox gets cluttered with guild mail with the assumption that guilds are not credit card companies (joke about how much mail I get from them ) and also people keeping the mail around without deleting (just like you would delete any of your other mail).
Though, it is still a good point, because their are exceptions.
I do agree with Seyo though, that getting the message of the day in the text box would be a great start!
Member of Knights Templar [KT] – http://knights-templar.com