snail mail
纸笔信件 ，用于区分电子邮件
It is outdated to send snail mails. Almost all the people send emails nowadays.
寄纸笔信已过时了，大部分的人现在发电子邮件。
junk mail
垃圾邮件
It seems to be unlikely not to receive any junk mail when you check your email. What you can do is to delete it with patience.
当你收电子邮件时，没收过垃圾邮件似乎是不太可能发生的事。你能做的只有耐心的把它删掉。
by return mail
回复信
Since the bill is overdue, would you please send us your check back by return mail?
由于这张账单过期未缴，能否请你用回函寄回你的支票呢？
best things come in small packages
好东西往往是小东西
Jenny always hates to be so short and tiny. However, her mother always says to her that best things come in small packages.
珍妮很讨厌自己又矮又小，但是她妈妈总是告诉她，麻雀虽小，五脏俱全。
a dear John letter
分手信
Susan doesn't love her boyfriend any more. She plans to send him a dear John letter.
苏珊不再爱她的男朋友了，她计划写封分手信给他。
bread and butter letters
感谢款待的信
Karen just had the meeting with Mr. and Mrs. Brown. After she went back to the office, she spent some time writing bread and butter letters to them.
凯伦刚刚和伯朗夫妇见面，回到公司后，她花了一些时间写感谢款待的信给他们。