mailer

[mey-ler] /ˈmeɪ lər/
noun
1.
a person who mails or prepares material for mailing.
2.
a container, as a mailing tube or protective envelope, for mailing papers, books, merchandise, etc.
3.
an advertising brochure, form letter, or the like, sent out in the mail.
4.
mailing machine.
5.
Archaic. a mailboat.
Origin
1880-85, Americanism; mail1 + -er1
British Dictionary definitions for mailers

mailer

/ˈmeɪlə/
noun
1.
a person who addresses or mails letters, etc
2.
(US & Canadian) a machine used for stamping and addressing mail
3.
(US & Canadian) a container for mailing things

Mailer

/ˈmeɪlə/
noun
1.
Norman. 1923–2007, US author. His works, which are frequently critical of modern American society, include the war novel The Naked and the Dead (1948), An American Dream (1965), his account of the 1967 peace march on Washington The Armies of the Night (1968), The Executioner's Song (1979), and Barbary Shore (1998)