A secretary wrote this letter for Paul (Romans 16:22; 1 Peter 5:12). Now Paul picks up the pen to add a final greeting written by his own hand (see 1 Corinthians 16:21; Galatians 6:11; Colossians 4:18; Philemon 1:19). He does this because he suspects someone is using his name and circulating a letter he did not write (2 Thessalonians 2:2). He emphasizes this step to prove the letter is truly from him.