standard mail (bulk rate) advantages

low cost

the post office gives standard mail users a low postage rate.
up to 3.3 ounces: while first class postage increases with every ounce, standard mail gives you the same low rate of postage up to 3.3087 ounces.

incremental postage increase

after 3.3 ounces, postage goes up incrementally as the weight goes up


standard rate disadvantages

slow delivery

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

not required to return mail

the post office is not required to return undeliverable mail, and in fact throws most undeliverable standard mail away. while a mailer can use an endorsement to be notified of moves or bad addresses, it is not a free service. much of this has been mitigated by new ncoa (national change of address) regulations and move update requirements.

weight restriction

weight of a single piece cannot exceed 1 pound, unless your piece qualifies for bulk printed matter.

qualification

to qualify for standard mail, one must have 50 lbs. or 200 pieces of mail. either way, all the pieces must have identical weight.