email_address = input("What is your email address? ")
while "@" not in email_address:
    email_address = input("Your email address must have '@' in itnPlease write your email address again: ")
    if len(email_address) <= 6 :
        email_address = input("Your email address is too shortnPlease write your email address again: ")
    if "." not in email_address:
        email_address = input("Your email address must have '.' in itnPlease write your email address again: ")
while "." not in email_address:
    email_address = input("Your email address must have '.' in itnPlease write your email address again: ")
    if len(email_address) <= 6 :
        email_address = input("Your email address is too shortnPlease write your email address again: ")
    if "@" not in email_address:
        email_address = input("Your email address must have '@' in itnPlease write your email address again: ")

email_address = check_email_contains(input("What is your email address? "), "@.")

def check_email_contains(email_address, characters, min_length=6):
    while True:
        for character in characters:
            if character not in email_address:
                email_address = input("Your email address must have '{}' in itnPlease write your email address again: ".format(character))
                continue
        if len(email_address) <= min_length:
            email_address = input("Your email address is too shortnPlease write your email address again: ")
            continue
        return email_address