The Epistles to Timothy and Titus are exactly what they say they are: epistles, or letters. In fact, because these three are so similar in content, they're often grouped together and called "The Pastoral Epistles." No, that doesn't mean they're all about farming. Instead, they're letters that offer guidance for the church. Just like a shepherd leading his flock (and congregation) to greener pastures.
So we're sorting through some really old mail, right? Well, kind of. While lots of New Testament books are traditional letters offering advice from everyone's favorite apostle, these three theological gems probably weren't originally sent as a letters.
Scholars believe that an anonymous guy (sometimes called the Pastor) wrote 1 Timothy, 2 Timothy, and Titus on his own to address whatever problems his community of Christians was having. Since Paul already had all those hard-won apostolic credentials, the author used Paul's name to give his message more oomph. It was a clever move. And since this was a pretty common practice in ancient times, we can't call this guy out too much (after all, he did make it into the Bible, so his spin on things couldn't be that bad).
Bottom line: even though these three books are written in the style of letters, they probably never made it through the mail to anyone.
Hey, at least the Pastor saved on stamps.