BLOC
The last part of a letter is the signature.
Technically, "epistle" means a letter. The ending of a letter is usually called a "closure," which is simply a polite and accepted form of ending a letter. For example: "Sincerely yours, XYZ"
valediction
viper
suffix
titled
covey
There is a city in Utah called Tropic.
alliance
covey (quail)
the signature of a letter is called the complimentary close or ending
The ending may include a "Complimentary close" such as Very truly yours, Cordially, Sincerely, etc. The "Signature" would follow the close.