phpbb_ynh/sources/phpBB/language/en/email/group_added.txt

Subject: You have been added to this usergroup

Congratulations,

You have been added to the "{GROUP_NAME}" group on "{SITENAME}".
This action was done by a group leader or the site administrator, contact them for more information.

You can view your groups information here:
{U_GROUP}

{EMAIL_SIG}