(KJV)1 Corinthians 5:9
I wrote unto you in an epistle not to company with fornicators:
It would seem in the above text Paul is referring to an epistle he had written before to the church at Corinth
(KJV)1 Corinthians 5:11
But now I have written unto you not to keep company, if any man that is called a brother be a fornicator, or covetous, or an idolater, or a railer, or a drunkard, or an extortioner; with such an one no not to eat.
In the above verse he now seems to make a distinction between the epistle which he was now writing to the church at Corinth & the former one by using the words "but now"in reference to his current epistle
In the current epistle he seems to be reiterating what he had previously said in the former concerning sexual immorality. Could there be another epistle to the Corinthians before this one where he admonishes them concerning sexual immorality?