Many discussions of attorney-client privilege focus on the attorney's responsibilities to protect against disclosure of privileged and confidential matters. Is the communication method secure enough? Is the office or storage space for documents secure enough? Do online file storage services utilize good enough encryption and security? Does the attorney protect computer files with adequate passwords, etc.?
A recent case from California points to the ability of the client to engage in behavior which will waive the privilege and allow disclosure of those otherwise confidential communications. Fourth Dimension Software v. Der Touristik Deutschland, GmbH involved a confidential email sent to a company chief executive officer by the company's lawyer. That is the type of communication that is normally not subject to disclosure. However, the CEO forwarded the email to his hotel's front desk for printing and pickup. The disclosure to the hotel staff rendered the communication no longer confidential.
So, a word to the wise.
For the communication to be privileged, it must be between only the attorney and the client(s).
When third parties are brought into the communication (whether by being present in person or by being copied on emails or by being forwarded copies of communications, that communication is likely no longer protected. There are some exceptions where the third party is part of the legal team. But in general, mothers, aunts, girlfriends, boyfriends, engaged persons, etc. are not going to fit those exceptions. Communications involving those people are often helpful and necessary, but they should not involve communications that the client or the attorney want to be confidential.
When either the attorney or the client handles confidential communications in a way that makes it available to third parties where that is not necessary to accomplish the communication, that may waive the privilege.