If preaching can be for the church, can teaching be for the lost? YES.
Matthew 28:19 KJV
Go ye therefore, and teach all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Ghost:
Acts 5:25 KJV
Then came one and told them, saying, Behold, the men whom ye put in prison are standing in the temple, and teaching the people.
2 Timothy 1:11 KJV
Whereunto I am appointed a preacher, and an apostle, and a teacher of the Gentiles.
Teaching is the impartation of information. One can teach sinners the truth about Jesus. One can teach Christians the truths of God's Word.
Teaching is in large measure the content of preaching. The purpose of preaching is to teach people about God, and teach them to believe and obey Him.
Teaching is often how God's truth is proclaimed (preached) to both the lost and the saints. Can there be any preaching that is utterly devoid of teaching content? Can you preach at all without teaching (or attempting to teach) SOMETHING? And when teaching God's Word, are you not proclaiming Christ? Are you not testifying as a witness, delivering the testimony of His original witnesses? Are you not announcing some good news?
Why, YES.