mailing (2) an envelope, a box, etc. for sending small things by mail(邮件封套或盒子等)信封◆makers of protective mailers保护性邮件包装用品制造商a person or company that sends a letter, package, etc.邮寄者◆Costs are rising fast for bulk mailers.大宗邮递的成本在迅速上升。a program that sends email messages电子邮件程序self-mailer