Snail mail or smail (from snail + mail) is a dysphemistic retronym — named after the snail with its slow speed — used to refer to letters and missives carried by conventional postal delivery services. The phrase refers to the lag-time between dispatch of a letter and its receipt, versus the virtually instantaneous dispatch and delivery of its electronic equivalent, e-mail. It is also known, more neutrally, as paper mail, postal mail, land mail, or simply mail.

Snail mail is also a term used in reference to penpalling. Snail mail penpals are those penpals that communicate with one another through the postal system, rather than on the internet which is becoming the standard form of communication for penpals.

Some online groups also use paper mail through regular gift or craft hot topics. In some countries services are available to print and deliver emails to those unable to receive email, such as the elderly.

This term was used at least as early as 1981 in the animated feature Strawberry Shortcake in Big Apple City, but not in the above sense contrasted with electronic mail, but rather as a rhyming joke to describe mail being delivered by an actual snail. Strawberry receives her letter three weeks late because, as the snail character admits, "Snail mail, she is slow".

An earlier use of this version of the term is attributed to the author Arnold Lobel in his story titled "The Letter" in the 1970 book titled, "Frog and Toad are Friends" in which Frog gave a letter to Snail to be delivered to Toad which took Snail four days to deliver.