The conditions of sending mail to my server are as follows:
A signature will in no way restrict my use of your message. You sent the message to me because you want me to read it (it was not mis-sent, my mail server does not accept mis-addressed mail). I will keep the message as long as I like either deliberately or because I forgot to delete it.
I reserve the right to publish any email that is threatening (including any threats of legal action). I don’t like being threatened and part of my defence is to publish such threats at an appropriate time. Anyone who is considering the possibility of threatening me should consider when their threat may re-appear.
I reserve the right to publish any email that is abusive/profane, is a confession of criminal or unethical behaviour, or is evidence that the sender is a liar or insane.
I reserve the right to forward all amusing email to my friends for their enjoyment.
My mail server will now provide the URL of this page to everyone who connects at the first stage of the SMTP protocol. When a mail server continues the connection that indicates acceptance of these conditions.
This doesn’t mean that I wildly forward email and business discussions are kept confidential of course. I expect that most people don’t keep mail secret when it matches the conditions in my list above, unlike most people I’m publishing the list of reasons.