Python script only downloading 3 emails

Question

I am trying to write a script that will scan through all emails from the past year. I can only get it to download the top 3. The tutorial I am following doesn't explain anywhere I can change the number of emails it downloads. Here's the code so far.

# user credentials
email_user = input('Email: ')
email_pass = input('Password: ')

# connect to imap
mail = imaplib.IMAP4_SSL("imap.gmail.com",993)

#login
mail.login(email_user, email_pass)

#select folder
mail.select("INBOX","SPAM")

#filter emails by header with receipt or invoice
type, data = mail.search(None, '(SUBJECT "Invoice")')
mail_ids = data[0]
id_list = mail_ids.split()

for num in data[0].split():
    typ, data = mail.fetch(num, '(RFC822)' )
    raw_email = data[0][1]
# converts byte literal to string removing b''
    raw_email_string = raw_email.decode('utf-8')
    email_message = email.message_from_string(raw_email_string)
# downloading attachments
    for part in email_message.walk():
        # this part comes from the snipped I don't understand yet... 
        if part.get_content_maintype() == 'multipart':
            continue
        if part.get('Content-Disposition') is None:
            continue
        fileName = part.get_filename()
        if bool(fileName):
            filePath = os.path.join('/Users/benbuechler/Desktop/Keepr Receipt Storage', fileName)
            if not os.path.isfile(filePath) :
                fp = open(filePath, 'wb')
                fp.write(part.get_payload(decode=True))
                fp.close()
            subject = str(email_message).split("Subject: ", 10)[1].split("\nTo:", 10)[1]
            print('Downloaded "{file}" from email titled "{subject}"'.format(file=fileName, subject=subject))

for response_part in data:
        if isinstance(response_part, tuple):
            msg = email.message_from_string(response_part[1].decode('utf-8'))
            email_subject = msg['subject']
            email_from = msg['from']
            print ('From : ' + email_from + '\n')
            print ('Subject : ' + email_subject + '\n')
            print(msg.get_payload(decode=True))