The only time that I use the client's account to post or send email is when it is related directly to their site.

For example, if I am sending a Unity Email to the Boonex Staff (for admin reasons) and want a trace of the thread available for my clients, I will use that account. Also, when posting bugs for the patches, I posted a few from that account (since I was on-site at the client location, and tracking down the bugs at the time), otherwise, I agree. All correspondence should be done through see more my personal account.

I also think that voting etc, should only be done through one account. Otherwise it is an abuse.