To the saints and faithful brethren in Christ which are at Colosse:
Colossians 1:2
"This letter was written by Paul, an apostle of Jesus Christ (1:1).
Though he did not personally know the recipients, Paul was
acquainted with them through Epaphras.
Epaphras probably planted the church in Colossae, judging from the fact that the believers there first learned the gospel from him (1:7).
Afterwards he served as their minister and informed the apostle of their conversion (1:7-8).
Colossians 1:2
"This letter was written by Paul, an apostle of Jesus Christ (1:1).
Though he did not personally know the recipients, Paul was
Epaphras probably planted the church in Colossae, judging from the fact that the believers there first learned the gospel from him (1:7).
Afterwards he served as their minister and informed the apostle of their conversion (1:7-8).
The testimony of the early church, including such key figures as Irenaeus, Clement of Alexandria, Tertullian, Origen, and Eusebius, confirms that the opening claim is genuine.
Additional evidence for Paul’s authorship comes from the book’s close parallels with Philemon, which is universally accepted as having been written by Paul. Both were written (ca. A.D. 60-62), when Paul was a prisoner in Rome (4:3, 10, 18; Philemon 9, 10, 13, 23); plus the names of the same people (e.g., Timothy, Aristarchus, Archippus, Mark, Epaphras, Luke, Onesimus, and Demas), appear in both epistles, showing that both were written by the same author at about the same time.
Colossians was likely penned, as were Ephesians, Philippians, and Philemon, during Paul’s first imprisonment at Rome (1:24; 4:18). The numerous parallels of vocabulary and matters discussed in Ephesians and Colossians link these epistles together. Also, there are many personal references common to Philemon and Colossians." BooksOfTheBible