smtp.py

import smtplib
import ssl

SENDER_EMAIL = '[email protected]'
RECEIVER_EMAIL = '[email protected]'
SERVER_API_TOKEN = '…'

for host in ['legacy-smtp.postmarkapp.com', 'smtp.postmarkapp.com', 'future-smtp.postmarkapp.com']:
	for port in [25, 2525, 587]:
		context = ssl.create_default_context()

		with smtplib.SMTP(host, port) as server:
			print(server.noop())
			server.ehlo()
			server.starttls(context=context)
			server.ehlo()
			server.login(SERVER_API_TOKEN, SERVER_API_TOKEN)
			server.sendmail(SENDER_EMAIL, RECEIVER_EMAIL, f'host={host} port={port}')