Your for loop is not right, if you need the index in the for loop use:
for index, item in enumerate(emails):
# whatever (but you can't remove element while iterating)
In your case, Bogdan solution is ok, but your data structure choice is not so good. Having to maintain these two lists with data from one related to data from the other at same index is clumsy.
A list of tupple (email, otherdata) may be better, or a dict with email as key.