Nice, good job.
There are several
join_email.html -> email after joining
join_existing_email.html -> email after joining from user panel ( secondary websites, same account )
join_email_admin.html -> Email to list admin that someone joined
join_premium_email_admin.html -> email to list admin, someone bought premium membership, waiting to be approved
join_premium_email_admin_approved.html -> email to list admin, auto approval premium membership bought
join_premium_email_user.html -> email to the one buying premium membership, telling them its waiting to be approved
join_premium_email_user_approved.html -> email to the one buying premium membership, auto approval
lost_pw_email.html -> email containing the validation link to reset password
premium_app_email.html -> when premium approval is enabled, send out once admin approves it
premium_rej_email.html -> when premium approval is enabled, send out once admin rejects it
premium_end_email.html -> When premium membership of a user ends
user_cp_login_email.html -> Part of 2step login authentication. If user selects email in his account settings. Once he logins he receives this with a link in order to validate his login
All templates make use of many language tags looking like this: {$lng->some_string}
These can be edited via admin manage languages by searching for "some_string"