“The salutation of Paul with mine own hand, which is the token in every epistle: so I write.”
King James Version (KJV)
2Th 3:17 With mine own hand. Here he adds the salutation in his own handwriting. The Epistle thus far had been written by one to whom he dictated, as was his custom, but he now adds his autograph. Which is the token of every epistle. This autograph was proof of the genuineness. Their attention is perhaps called to this on account of a spurious epistle (2Th 2:2).