BSA requires "two-deep leadership" which means that adults are not allowed to have one-on-one contact with Scouts. This applies to in-person meetings as well as emails. Scouts are required to copy a second adult on emails to a Scout leader. The second person could be another Scout leader (MB Counselor, Eagle Project Coach, etc.) or a Scout's parent.
When emailing a Leader, Scouts should make sure they:
Address the person who is receiving the email by name (Dear Mr. LaMagna)
Write your message
Complete the email by signing your name (Sincerely, Joe Scouter)