I have all my users in 365 and they are happily emailing away. I have discovered how to set up distribution groups and to give them an external address for public access. I have security groups that I thought could be emailed but that doesn't seem to work. My question is this. I want to send an email to the English department. Is the preferred method to set up a distribution group and add all the English staff to that group or is there a preferred method that I'm not seeing. The reason I ask is that I have already created a group and added all the staff to it only to find that I can't mail the group. Is there a way to add users to groups and them to use that grouping for team sites so that I only have to create the groups once?