These are a few ethical questions, touched on below, that have arisen in the context of ever-increasing reliance on, ease of use of, and advancement of technology in the practice of law. The weight of current opinion appears to be that communicating with clients via e-mail poses no particular risk of disclosure of confidential client communications.
Intentional interception is viewed as remote, and indeed is unlawful.
The inference is that, therefore, no waiver occurs by inadvertent disclosure of the contents of e-mails. The problem is not so much that e-mail will be hacked into, or sniffed on its way into cyberspace, or otherwise be subject to snooping by some illicit means. If your clients choose e-mail communication, think about putting together a waiver letter regarding the risks of the mode of communication. Advise the client of the password separately, by phone for instance. The document cannot be opened without the password.