>>> from itertools import permutations
>>> perms = [''.join(p)+"@gmail.com" for p in permutations('abc', 3)]
>>> for x in range(0, len(perms)):
...     print (perms[x])
... 
abc@gmail.com
acb@gmail.com
bac@gmail.com
bca@gmail.com
cab@gmail.com
cba@gmail.com
>>>