How can I make Safari or Chrome remember my messages in contact forms?

As a customer, I contact businesses through contact forms on their websites, and often I forget the exact wording of the message and when I sent it. (Often, I need to re-send messages when I don't receive a reply and an email address isn't listed on the site.) How can I make Safari remember the contents of the ` and fields of the ` element? Preferably timestamped. Is there a Safari (or Chrome) extension that does this? This question applies mostly to Mac OS X, but also relevant for iOS devices.