Python3: メールの送信 （添付ファイル付き）

こちらのプログラムを改造して、添付ファイルを送るようにしました。
Python3: Starttls でメールの送信
attachements/linux_logo.gif というファイルを添付するサンプルです。

coreserver_attache.py

# ! /usr/bin/python3
# -*- coding: utf-8 -*-
#
#	coreserver_attache.py
#
#						Apr/17/2021	
# --------------------------------------------------------------------
import	os
import	sys
import	socket
from dotenv import load_dotenv
import	email
from email.mime.text import MIMEText
from email.utils import formatdate
from email.message import EmailMessage
import imghdr
# --------------------------------------------------------------------
from send_starttls import send_starttls_proc
# --------------------------------------------------------------------
def attach_image_proc(message,img_data,filename):
    try:
        message.add_attachment(img_data,maintype='image',
            subtype=imghdr.what(None,img_data),filename=filename)
    except Exception as ee:
        sys.stderr.write("*** error *** in message.add_attachment ***\n")
        sys.stderr.write(str(ee) + "\n")
#
    return message
# --------------------------------------------------------------------
def create_message_proc(mail,file_attach):
	message = EmailMessage()
	contents = 'Hello, Good Afternoon! on Apr/17/2021 PM 20:21\n'
	contents += 'Apr/17/2021 PM 20:03\n'
	contents += 'こんにちは。\n'
	contents += 'python3\n'
	contents += ' ' + socket.gethostname ()

	message.set_content(contents)
	message['Subject'] = 'Hello Apr/17/2021 PM 20:21'
	message['From'] = mail['from']
	message['To'] = mail['to']
	message['Date'] = formatdate ()
#
	fp = open(file_attach,'rb')
	img_data = fp.read()
	fp.close()
#
	for suffix in [".jpg",".png",".bmp","gif"]:
		if (file_attach.endswith(suffix)):
			message = attach_image_proc(message,img_data,file_attach)
#
	return message
# --------------------------------------------------------------------
sys.stderr.write ("*** 開始 ***\n")
dotenv_path = '.env'
load_dotenv(dotenv_path)
mail = {}
mail['server'] = os.environ.get("SERVER")
mail['port'] = os.environ.get("PORT")
mail['usr'] = os.environ.get("USR")
mail['password'] = os.environ.get("PASSWORD")
mail['from'] = os.environ.get("FROM")
mail['to'] = os.environ.get("TO")

file_attache = "./attachements/linux_logo.gif"

message = create_message_proc(mail,file_attache)

send_starttls_proc (mail,message)
#
sys.stderr.write ("*** 終了 ***\n")
# --------------------------------------------------------------------

次のファイルはこちらです。
Python3: Starttls でメールの送信

send_starttls.py
.env