Express Mail
This money-back guaranteed overnight to two-day service includes tracking, proof of delivery, and insurance up to $100. Additional insurance up to $5,000 may be purchased for merchandise. Sunday and holiday delivery is available to many destinations for an additional $12.50. Express Mail envelopes and boxes are available at many Post Offices at no charge and may be ordered from www.usps.com.

Priority Mail
This service is typically used to send documents, gifts, and merchandise. Priority Mail envelopes and boxes are available at many Post Offices at no charge and may be ordered from www.usps.com.

First-Class Mail
This service (or Express Mail or Priority Mail) is required for personal correspondence, handwritten or typewritten letters, and bills or statements of account. It also may be used for most mailable items, including advertisements and light weight merchandise.

Parcel Post
Items such as gifts and merchandise can be sent using Parcel Post.

Media Mail
Books of eight or more printed pages with only incidental blank spaces and no advertising except for incidental announcements of books, 16-millimeter or narrower width films in positive print for viewing (excluding films sent to or from commercial theaters), catalogs of such film of 24 pages or more, printed music (bound or in sheet form), printed objective test materials and accessories, sound recordings, video recordings, play scripts and manuscripts, printed educational reference charts, loose-leaf pages and their binders consisting of medical information, and computer-readable media containing prerecorded information up to 70 pounds can be sent as Media Mail.