>>> email.utils.getaddresses(['friend@email.com, John Smith <john.smith@email.com>,"Smith, Jane" <jane.smith@uconn.edu>'])
[('', 'friend@email.com'), ('John Smith', 'john.smith@email.com'), ('Smith, Jane', 'jane.smith@uconn.edu')]

from email.utils import getaddresses

addrstring = ',friend@email.com, John Smith <john.smith@email.com>,"Smith, Jane" <jane.smith@uconn.edu>,'

def addrparser(addrstring):
    addrlist = ['']
    quoted = False

    # ignore comma at beginning or end
    addrstring = addrstring.strip(',')

    for char in addrstring:
        if char == '"':
            # toggle quoted mode
            quoted = not quoted
            addrlist[-1] += char
        # a comma outside of quotes means a new address
        elif char == ',' and not quoted:
            addrlist.append('')
        # anything else is the next letter of the current address
        else:
            addrlist[-1] += char

    return getaddresses(addrlist)

print addrparser(addrstring)

[('', 'friend@email.com'), ('John Smith', 'john.smith@email.com'),
 ('Smith, Jane', 'jane.smith@uconn.edu')]