Priority Mail

Can a regular letter envelope be sent through USPS Priority Mail?
I have some event tickets I need to mail to someone, but I don’t want to pay the almost $5 for a Priority Mail documents envelope from the post office. Can I mail them in a regular letter envelope but still use the Priority Mail service?
Thanks.
Priority Mail costs the same whether you use the USPS envelopes or not. It’s $4.60 for anything under one pound or anything that fits in their flat-rate envelope.
For a regular letter, priority mail probably isn’t going to be much faster than regular first-class mail. You can see the service options at http://postcalc.usps.gov and compare prices and how long it will take to get there.
Setrise – Priority Mail (Original Mix)