After following the steps in:
How can I undo these settings?
How can I set Mail.app back to being the default mailto: protocol handler?
I tried unsetting the mailto: protocol in chrome://settings/handlers, but the only result is that now mailto: links don't open at all. (They still switch focus to Chrome.)
According to this answer, the file that needs to be edited is ~/Library/Preferences/com.apple.LaunchServices.plist. However, checking the file contents with the file command shows that it is a binary file:
$ file /Users/(me)/Library/Preferences/com.apple.LaunchServices.plist
/Users/(me)/Library/Preferences/com.apple.LaunchServices.plist: Apple binary property list
What else can I try?
(I am running Mac OS 10.7.4.)