Ephesians is among Paul’s letters referred to as the Prison Epistles. It is generally assumed that Paul wrote these epistles during his imprisonment in Rome though there is some evidence to support the suggestion that Paul may have also been imprisoned in Ephesus and wrote one or two of the Prison Epistles during that period. If that is the case, then the dating of the early 60’s is drawn into question though I believe that possibility impacts the dating of Philippians much more than Ephesians.
Determining the purpose for this epistle is difficult. The letter is solemn with a very serious tone though does not appear to have been written to address the specific needs of a church like many of Paul’s other letters. It is clear that Ephesians was meant to provide instruction to Paul’s readers though Carson and Moo point out that there is no unanimity in understanding the letter’s aim.
Ephesians does appear to be directed towards Gentile believers though it does not appear to have been written to address a crisis or other urgent need. It has been suggested that Ephesians may have been a circular letter intended to be delivered to a number of churches in Asia Minor. Many of the surviving manuscripts omit the words “at Ephesus” in 1:1. Also in support of the idea that Ephesians may have been an encyclical is the impersonal nature of the letter. Since Paul worked in Ephesus for about three years, and since his normal practice was to mention his many friends in the churches to which he wrote, a strong case can be made for the theory that Ephesians was a circular letter.
Lea and Black point out that an equally convincing case can be made for an original Ephesian destination since the words “in Ephesus” are early and widespread. They also point out that the three most widely read Pauline letters – Romans, 1 Corinthians, and Ephesians – all appear to have had their place destinations tampered with.
Unlike other Pauline writing, there is no false teaching being confronted nor does it appear that Paul is confronting opposition. It would seem that Ephesians is simply a general statement of Christian truth concerning the church, Christian unity, and the Christian walk.
 Lea, Thomas D., and David Alan Black. The New Testament: It's Background And Message (2nd ed). (Nashville: Broadman & Hollman Publishers, 2003), 438. The authors go on to mention that the better Paul knew his audience, the more impersonal his letters appeared to have been. For example, while Ephesians is very impersonal even though Paul knew the congregation so well while Romans has many personal references even though Paul never visited the church there.