students="John Dee johndee@gmail.com 555-555-5555,Jane Bee janebee@gmail.com 555-555-5555,Sarah Zee sarahzee@gmail.com 555-555-5555"

def alphaOrder(students):
    mylist = []
    splitter = students.split(',')

    for i in splitter:
        mylist.append(i)

    mylist.sort(key=lambda n: split(' ')[1])
    print(mylist)

alphaOrder(students)

res = sorted(students.split(','), key=lambda x: x.split()[1])

['Jane Bee janebee@gmail.com 555-555-5555',
 'John Dee johndee@gmail.com 555-555-5555',
 'Sarah Zee sarahzee@gmail.com 555-555-5555']