#4 Explain the appropriate boundaries of confidentiality in biblical Counseling/discipleship

First of all, sin has no biblical right to privacy; however, there is definitely need for discretion in revealing of details, and/or circumstances. If an individual is committing adultery, for example, the spouse has a right to know. That doesn't mean the counselor ought to be the one to tell the offended spouse. If the individual is unwilling to confess his/her sin to his/her spouse, it may be necessary to inform the spouse of the unrepentant individuals act. It also wouldbe relevant to refer to Matthew 18:15-17 "If your brother sins against you/ go and tell him his fault between you and him alone. If he listens to you, you have gained your brother. But if he does not listen, take one or two others along with you, that every charge may be established by the evidence of two or three witnesses. If he refuses to listen to them, tell it to the church. And if he refuses to listen even to the church, let him be to you as a gentile and a tax collector."
A man should not counsel a woman without the presence of either her husband, or another woman- prefferably his wife. It would be wise for the counselor's spouse, an elder, or other trustworthy person in a leadership position, to have access to the emails being passed between the counselor and his/ her counselee- especially if the persons involved are of the opposite gender. The counselee should, obviously, be made aware of this arrangement prior to giving access, and or counseling. The necessity for these precautions are derived from 1 Thessalonians 5:22 "Abstain from all appearances of evil." 1 Corinthians 6:18 "Flee from sexual imorality..." and 2 Timothy 2:22-23 "So flee youthful passions and pursure righteousness, faith, love, and peace, along with those who call on the Lord from a pure heart. Have nothing to do with foolish controversies; you know that they breed quarrels." These precautions are for the protection of both parties to prevent false accusations, misunderstandings, or inappropriate behavior on the part of either the counselor, and/or the counselee. Galatians 6:1-2 "Brothers, if anyone is caught in any transgression you who are spiritual should restore him in a spirit of gentleness. Keep watch on yourself lest you too be tempted. Bear one anothers burdens and so fulfill the law of Christ."
A counselor ought never to participate in gossip in general, but more specifically in regard to their subjects. These people are confinding with the counselor privately and unless the serson's sin is affecting or involving another individual it should not be shared even with a spouse (with the exception mentioned above for safety purposes.)