Cmd+drag&drop and the @ symbol does email?

Cmd+drag&drop usually copies the selected data. However, if one of the characters in the selection is the “@” symbol, it opens my mail application (Mailsmith, in this case) and creates a new message addressed to what it thinks is an email address.

This is in the DTP Manual on p. 130: “Open clicked URL within text or web views in default application (e.g. your default Internet browser),”

For example:

• in - select the part and do a cmd-click. A new email is created.
• in bob@there.x - select the @there.x part - new email is created.
• in bob@there - select the @there - now a normal drag&drop happens. So it seems to look for the “email address” pattern.

I can see the utility of this. But it makes it impossible to grab the last part of an email address and duplicate it with drag-and-drop … and all things considered, I’d rather be able to drag-and-drop.

Is there a way to turn it off?