Our mouth is open refers to what he has just said; this is figurative language meaning that he has “spoken frankly” (Good News Translation, New Revised Standard Version) without holding anything back. Revised English Bible has “we have spoken very frankly,” while Moffatt translates “I am keeping nothing back from you,” and Phillips reads “we are hiding nothing from you.”

The term of address, Corinthians, will fit more naturally at the beginning of the verse in many languages. Note that Good News Translation fills it out by saying “Dear friends in Corinth,” and New Jerusalem Bible has “people of Corinth,” since a more literal translation may sound too harsh.

Our heart is wide is also figurative language. The meaning is not so much that Paul and his associates have told the Corinthians everything that they were thinking. A broadened heart is rather the sign of great affection (see 7.3). In view of this some possible models are “we love you with all our hearts” (Good News for the World) or “there is room in our hearts for you” (Contemporary English Version).

Quoted with permission from Omanson, Roger L. and Ellingworth, Paul. A Handbook on Paul’s Second Letter to the Corinthians. (UBS Handbook Series). New York: UBS, 1993. For this and other handbooks for translators see here .