I think it is common sense that PM content or Email content is supposed to be kept between the sender/receiver as stated here:
Privacy in email
In personal email communications, there has always been, and always should be, an expectation of privacy between the sender and the intended recipients of a message, enabling open communication with friends, colleagues, family, and others.
Privacy is compromised, however, if personal information or private email content is shared with parties other than the sender and intended recipients without their consent.
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I notice quite often here on the forum that members will and do have a tendency to quote from PM's/Emails on the open forum to make a point. This is really bad form in my opinion. If you have an issue with a PM you have received from another member you can notify me as to the complaint via PM (ie. commercial spam, etc) and I will take action on it if appropriate. There have been 4 recent examples of PM/emails being disclosed on the open forum, this is really poor manners in my opinion.
PM Email Etiquette
Moderators: MGV12, BKKBILL, Sometimewoodworker
Re: PM Email Etiquette
Netiquette Reminder: Don't disclose the Email or PM (private message) contents from another on the open forum.