Using xargs with vi...

To use xargs with vi, look for the -o or -t switch. This switch will in turn cause xargs to pass its terminal information to vi. This will allow vi to open with multiple windows.

Here is some a sample command line.
find .maildir/cur/ -type f|xargs grep -l -e "From:.*billybob"|xargs -o -n1 vi

This information was acquired from the manpage.