#!/usr/bin/perl -w
use strict;

my $string = 'sean@gmail.com, "richard J. Smith, M.D." <richard@gmail.com>, "john" <john@gmail.com>, <jack@gmail.com>';

$string =~ s/\"[\w .,]+"//g;

print $string;
#sean@gmail.com,  <richard@gmail.com>,  <john@gmail.com>, <jack@gmail.com>