Python script to send mail via Apple's iCloud. Be sure to setup an app specific password for and do not use or expose your iCloud password. https://support.apple.com/en-us/HT204397

smtp_icloud.py

import smtplib

#email.mime.multipart is specific to python3
from email.mime.multipart import MIMEMultipart
from email.mime.text import MIMEText

msg = MIMEMultipart()
msg['From'] = 'sendfrom@mail.com'
msg['To'] = 'sendto@mail.com'
msg['Subject'] = 'Subject'
message = 'Message body'
msg.attach(MIMEText(message))

mailserver = smtplib.SMTP('smtp.mail.me.com', 587)
# identify ourselves
mailserver.ehlo()
# secure our email with tls encryption
mailserver.starttls()
# re-identify ourselves as an encrypted connection
mailserver.ehlo()
mailserver.login('iCloud ID', 'app-specific password')
mailserver.sendmail('sendfrom@mail.com',
                    'sendto@mail.com', msg.as_string())

mailserver.quit()

I do not. But if you are using a Google example, I would imagine using iCloud's IMAP settings should work also.

#  Connect to the iCloud IMAP Mail Server
imap.put_Ssl(True)
imap.put_Port(993)
success = imap.Connect("imap.mail.me.com")
if (success != True):
    print(imap.lastErrorText())
    sys.exit()

#  The username is usually the name part of your iCloud email address
#  (for example, emilyparker, not emilyparker@icloud.com).
success = imap.Login("ICLOUD_USERNAME","ICLOUD_PASSWORD")
if (success != True):
    print(imap.lastErrorText())
    sys.exit()

I get to the point to actually download a list with all email and am able to read the UIDs but the emails don't contain anything. In all the gmail examples its as easy a calling the fetch method and getting the email with all its payload.
Sorry for not pointing this out in the first place.

Maybe try something like this?

#  Once the folder/mailbox is selected, the NumMessages property
#  will contain the number of emails in the mailbox.
#  Loop from 1 to NumMessages to fetch each email by sequence number.

n = imap.get_NumMessages()
bUid = False
for i in range(1,(n)-1):

    #  Download the email by sequence number.

    email = imap.FetchSingle(i,bUid)
    if (imap.get_LastMethodSuccess() != True):
        print(imap.lastErrorText())
        sys.exit()

    print(str(i) + ": " + email.ck_from())
    print("    " + email.subject())
    print("-")

#  Disconnect from the IMAP server.
success = imap.Disconnect()

What example did you use?

.get_NumMessages is not an IMAP4 command for me.

Exception has occurred: AttributeError
Unknown IMAP4 command: 'get_NumMessages'
File "/Users/lars/Desktop/Test/Test-Env/src/email.py", line 25, in
n = mail.get_NumMessages()