The phrase "class mail" refers to a specific category or type of mail service that offers different levels based on the speed of delivery and features provided. Full definition
Your Page traffic school completion certificate will be sent right to your mailbox via first class mail service. (drivinguniversity.com)
Your Rescue traffic school completion certificate will be sent right to your mailbox via first class mail service. (drivinguniversity.com)
Tip: If you are testing out a new lead list, use first class mail for your initial mailing and you will get returned mail to weed out the bad addresses. (openlettermarketing.com)