gpk@site.com  for 716745165214@kdf.net kglk@mail.ru lkjl@list.ru ncv@gmail.com
gpk@site.com  for 716745165214@kdf.net kglk@mail.ru lkjl@list.ru ncv@gmail.com
gpk@site.com  for 716745165214@kdf.net kglk@mail.ru lkjl@list.ru ncv@gmail.com

{gpk@site.com
{
16745165214@kdf.net : 3
kglk@mail.ru : 3
kjl@list.ru : 3
ncv@gmail.com : 3
}
}

#! /usr/bin/env python3.6
# -*- coding: utf-8 -*-
def reader(fname):
    d={}
    fromto={}
    df=[]

    file = open(fname,"r")
    for line in file:
#           print (line)
            ll=line.strip().split('for')
            sfrom=''.join(ll[0].split())
            sto=ll[1].split()
            if sfrom in fromto: # почему-то проверка не рботает
                df = fromto[sfrom]

            for i in range(len(sto)):
                    df.append(sto[i])

            fromto[sfrom]= df
            df.clear()

    print(fromto)

if __name__ == '__main__':
    reader('list-100.list')

from collections import Counter

log = """
gpk@site.com  for 716745165214@kdf.net kglk@mail.ru lkjl@list.ru ncv@gmail.com
gpk2@site.com  for 7167451652142@kdf.net kglk2@mail.ru lkjl2@list.ru ncv2@gmail.com
gpk@site.com  for 716745165214@kdf.net kglk@mail.ru lkjl@list.ru ncv@gmail.com
"""

pairs = Counter()
for line in log.splitlines():
    tmp = line.split()
    from_user = tmp[0]
    pairs.update((from_user, to_user) for to_user in tmp[2:])

print(pairs)

text = """
1. gpk@site.com  for 716745165214@kdf.net kglk@mail.ru lkjl@list.ru ncv@gmail.com
2. abc@site.com  for site@site.ru lkjl@list.com
"""

from collections import defaultdict
from_by_to_list = defaultdict(list)

for line in text.splitlines():
    line = line.strip()
    from_str, to_str = line.split('for')

    from_str = from_str.strip().split()[1]
    to_list = to_str.strip().split()

    from_by_to_list[from_str] += to_list

print(from_by_to_list)
print()

for k, items in from_by_to_list.items():
    print('{} ({}):'.format(k, len(items)))
    for i, x in enumerate(items, 1):
        print('    {}. {}'.format(i, x))

    print()

defaultdict(<class 'list'>, {'gpk@site.com': ['716745165214@kdf.net', 'kglk@mail.ru', 'lkjl@list.ru', 'ncv@gmail.com'], 'abc@site.com': ['site@site.ru', 'lkjl@list.com']})

gpk@site.com (4):
    1. 716745165214@kdf.net
    2. kglk@mail.ru
    3. lkjl@list.ru
    4. ncv@gmail.com

abc@site.com (2):
    1. site@site.ru
    2. lkjl@list.com