As long as the security group is Universal, as mentioned, you only need to add an email address and proxyaddresses in Attribute editor and wait for the sync to occur. Running todd's command in Exchange Powershell should do that for you, but it would be advisable to specify the addresses the group will use rather than accepting what Exchange sets by default, since you may end up with addresses that could be longer than you want.
Todd Nelson
Correct, Adam.
By default, mail enabling a mailbox or group without specifying an email address (in my prior code sample) will create an email address based on the email address policy.
But by specifying an email address when enabling the group or mailbox, like this...
OK thanks guys. I ran the commands on local Exchange 2013\ Exchange Management Shell and seems to have worked. Many thanks
Warm thanks to both for your assistance