>>> message = 'qwe r tyui opas dfg hjk lzxc vb n m'
>>> j, s = 1, ''
>>> for i in message: 
...    if not i.isspace():
...        s += i
...        j += 1
...    if not j % 8: s += ' '     
...   
>>> s
'qwertyu iopasdf ghjklzx cvbnm'

In [1]: from __future__ import print_function
In [2]: message = u'Здравствуйте меня зовут Андрей'
In [3]: for k,v in enumerate(message.replace(' ', ''), start=1):
   ...:     print (v, end='')
   ...:     if not k % 7: print (' ', end='')
   ...:     
Здравст вуйтеме нязовут Андрей

key = 'aaaaabbbbbabbbaabbababbaaababaab'
alphabet = 'abcdefghijklmnopqrstuvwxyz'
message = raw_input('Введите строку: ')
message = message.replace(" ", "")
message_length = len(message)
ostacha = len(message) % 5
prom = message[:-ostacha]
j, s = 1, ""
for i in prom:
    if not i.isspace():
        s += i
        j += 1
        if not j % 7: s += ' '     
print s

j, s = 0, ''
for i in message:
    if not i.isspace():
        s += i
        j += 1
        if not j % 7: s += ' ' 

message = message.replace(" ", "")

message_length = len(message)

ostacha = len(message) % 5
prom = message[:-ostacha]