import email
import imaplib
 
user='user@yandex.ru'
pasw = 'password'
 
M = imaplib.IMAP4_SSL('imap.yandex.ru')
M.login(user, pasw)
M.select('combain')
typ, data = M.search(None, 'ALL')
for num in data[0].split():
    typ, data = M.fetch(num, '(RFC822)')
    print 'Message %s\n%s\n' % (num, data[0][1])
M.close()
M.logout()

M = imaplib.IMAP4_SSL('imap.yandex.ru')
M.login(user, pasw)
M.select('combain')
typ, data = M.search(None, 'ALL')
for num in data[0].split():
    typ, data = M.fetch(num, '(RFC822)')
    raw = email.message_from_bytes(data[0][1])
    print (raw.get_payload(None,True))
M.close()
M.logout()