In versions of Mail prior to OS X 10.6, you could copy an email address from a message by Control-clicking on the address and choosing Copy Address from the contextual menu. As part of my job, I do this a lot -- users will email me, asking to look up their account name, for instance, so I need to paste their email address into a web form.
In 10.6, it seems someone at Apple decided that Copy Address should really mean Copy Name And Address And Add Angle Brackets Around The Address, because that's exactly what happens when you use Copy Address in Snow Leopard's Mail app. Instead of getting Sue_Sample@somesite.com on the clipboard, you get Sue Sample <Sue_Sample@somesite.com>.
Besides now having an incorrect name on the Copy Address contextual menu item (thought admittedly, the alternative is a bit lengthy), this behavior is incredibly irritating if you want only the email address on the clipboard. Thankfully, some engineer somewhere deep within Apple included a hidden preference to change this behavior -- and the fine folks at Mac Daddy World (the Ecamm Network blog site) dug deep and discovered this preference.
To revert to the 10.5-style behavior in Mail, first quit Mail then enter this command in Terminal:
defaults write com.apple.mail AddressesIncludeNameOnPasteboard -bool NO(For an easier method of implementing this feature, see this hint.) From now on, Copy Address will again do just what it claims to do. Thanks to @macminicolo and @CraHan for pointing me to the fix after I tweeted about this annoyance this morning!
Mac OS X Hints
http://hints.macworld.com/article.php?story=20091203062729936