Valediction n. : A farewell; a bidding farewell.

Example:
What's a good Valediction to use in an email?

Taxonomy
valediction, Grüßen, expression, recipient, English, German, faithfully, salutations, best regards, Hebrew, Madam, sentiments, obedient servant, hierarchical level, free encyclopedia, kind regards, sincères salutations, formal correspondence.

Defination from the web:
valediction (derivation from Latin vale dicere "to say farewell") is an expression used to say farewell, especially at the end of a letter, or ... The word valediction is commonly used in English to refer to a complimentary closing - a courteous, formulaic phrase preceding the writer's ...