/usr/share/phpbb3/www/language/fa/email/user_remind_inactive.txt is in phpbb3-l10n 3.0.10-4+deb7u3.
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1 2 3 4 5 6 7 8 9 10 11 | Subject: Inactive account reminder
Hello {USERNAME},
On {REGISTER_DATE} you registered a new account at "{SITENAME}". To date you have not activated this account which is a prerequisite for board login. For your convenience the activation link is repeated below.
{U_ACTIVATE}
Thank you for registering at "{SITENAME}", we look forward to your participation.
{EMAIL_SIG}
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