Basically you can feed it through a pipe with sed (or awk, but I am better with sed. The following recipe may not work for all of the cases you are interested in, but :
:0 fwh
* ^From.*some.*com
|sed s/fuzzy@some.com/myfirend@some.com/g
This will just pass the mail along for further operation, with
myfirend@some.com (did you mean myfriend? :-) substituted for
fuzzy@some.com.
If you want joe <fuzzy@some.com> to go to
joe@some.com (just a thought), try the following:
:0 fwh
* ^From.*joe.*some.com
|sed -e s/\ \<fuzzy//g -e s/\>//g
You need the backslashes for spaces, redirects (<,>) and of course other special characters.
Good luck, Chris