When writing a letter it typically starts out "Dear..." and then has the content, then before you sign it you might have a formal or informal (depending on who you're writing to) sign off, for example:
blah blah blah letter content blah blah.
Kind regards/Many thanks/Best wishes/Cheers!/etc
Does this final closing portion of your letter have a name?
For comparison, the middle portion of the letter is the body and the opener could be described as a greeting or, more accurately, the salutation. but I don't think this last bit could be called a farewell as such.
So what should it be called?