first class advantages

speedy delivery

first class mail, in-state, is generally delivered in 1 to 2 days, and rarely takes longer than a week to anywhere in the continental u.s. returned mail bad addresses and moves that are 12 to 18 months old come back to the sender at no charge. moves within 12 months automatically get forwarded (or could be directed by the use of postal endorsements) to come back to the sender. in either case, there is no charge.

postal employees try harder

postal employees are instructed to make every effort to deliver first class mail. no directional indicator? bad handwriting? if it's first class there's a good chance of arrival.

likely to be opened by the recipient

because things of importance are mailed first class (bills, travel confirmation, etc.) recipients often feel compelled to open their first class mail.

first class mail disadvantages

cost

the postage on first class mail is higher than some of the other classes of mail to compensate for the additional services provided.

weight / cost

standard mail keeps the same rate as long as the piece weighs less than 3.3 ounces. the cost of first class mail rises incrementally with every ounce.

weight restriction

weight of a single piece cannot exceed 13 ounces.