It would be great if site members in the "Send Email to All Members" list could be ordered by first or last name. Or if they could be put into groups (by different family names, for example), like a Yahoo! address book.
If you go to your site members page, and sort the view according to last name (or first), and then choose to send an email to all members, then you will see all the addresses in alphabetical order according to last name (or first name).
We do not yet have the groups feature available. I will make sure to pass on that request for future consideration.