Hiya!
I'm a Guild Master, and it is pretty hard to send people a news letter, reminders about events, and other various communications. I do this once in awhile, but it takes a fair amount of time to send out 70 - 100 identical in-game mails because there is no support for group mail. When you add guild improvements please at the very least add a mail to guild option in the guild menu for officers and GMs. This way it is only an additional guild option and doesn't require very much UI support. Ideally I would like the ability to make lists for my Lockdown team and things like that, but I can easily see the ROI for full support of mail doesn't make a lot of sense (as only a few GMs and Event organizers would really want this functionality). The mail to guild option should be super simple to implement and would be beneficial to guilds though.
Thanks for you time and consideration
Flawedknight
Well you probably don't need to be told you're not the first to suggest this, but I will anyway. That doesn't change the fact that I support the concept I guess.