Way too many people use Certified Mail when they should be using Certificate of Mailing instead. Where Certified Mailing gives you proof of delivery (and the date/time it was delivered) - a Certificate of Mailing provides proof of the date the package was mailed. So anything that requires the package be "received by" a specific date does in fact justify Certified Mail. However, anything that has a deadline of being "mailed by" a specific deadline (eg: all tax filings and payments in the US) only need a Certificate of Mailing which costs a small fraction of Certified Mail. With this tool here you can generate a printable PDF file with up to 8 pre-populated USPS Certificate of Mailing forms so you don't find yourself standing to the side of the line at the Post Office scrambling to fill in the addresses by hand in the too-small lines on the silly little PS3817 form.