Python3: POP3 でメールの受信

次の記事を参考にしました。
Pythonでメール受信; poplibのサンプルコード

get_pop3.py

# ! /usr/bin/python
#
#	get_pop3.py
#
#						Dec/09/2020
#
# --------------------------------------------------------------------
import os
import sys
import base64
import email
import poplib
import ssl
from email.header import decode_header, make_header
from dotenv import load_dotenv

# --------------------------------------------------------------------
sys.stderr.write("*** 開始 ***\n")
#
dotenv_path = '.env'
load_dotenv(dotenv_path)
#
server= os.environ.get("SERVER")
usr= os.environ.get("USR")
password= os.environ.get("PASSWORD")

port = 995

context = ssl.create_default_context()
popclient = poplib.POP3_SSL(server, port, timeout=10, context=context)
popclient.set_debuglevel(0)


auth_method = "user"

popclient.user(usr)
popclient.pass_(password)


download_num = 1
msg_list = []
msg_num = popclient.stat()[0]
sys.stderr.write("msg_num = %d\n" % msg_num)

if msg_num <= download_num:
	 download_num = msg_num
for i in range(download_num):
	 msg_bytes = b""
	 for line in popclient.retr(download_num)[1]:
		  msg_bytes += line + b"\n"
	 msg_list.append(email.message_from_bytes(msg_bytes))
popclient.quit()


for msg in msg_list:
	from_addr = str(make_header(decode_header(msg["From"])))
	subject = str(make_header(decode_header(msg["Subject"])))
	print("From:{}".format(from_addr))
	print("Subject:{}".format(subject))
	print()

	if msg.is_multipart() is False:
		payload = msg.get_payload(decode=True)
		charset = msg.get_content_charset()
		if charset is not None:
			payload = payload.decode(charset, "ignore")
		print(payload)
		print()
	else:
		for part in msg.walk():
			payload = part.get_payload(decode=True)
			if payload is None:
				continue
			charset = part.get_content_charset()
			if charset is not None:
				payload = payload.decode(charset, "ignore")
				print(payload)
				print()
#
sys.stderr.write("*** 終了 ***\n")
# --------------------------------------------------------------------

.env

SERVER = 'mail.example.com'
USR = '*****@example.com'
PASSWORD = '*********'

実行方法

./get_pop3.py

次の環境で動作を確認しました。

$ uname -a
Linux iwata 5.8.0-31-generic #33-Ubuntu SMP Mon Nov 23 18:44:54 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux
$ python --version
Python 3.8.6

imap で受信する方法はこちら
python でメールの受信