Python嵌入HTML图片发送邮件耗时过长问题及解决方法

问题场景 #

作为Python新手，我需要实现读取指定文件夹内的图片并将其嵌入邮件发送的功能。但测试仅处理1张图片时，程序运行5分钟仍未完成，只能手动终止。

解决方案 #

在smtp.sendmail()函数的第三个参数msg后添加.as_string()方法，将EmailMessage对象转换为字符串格式后再发送，解决了程序卡顿的问题。

完整代码 #

from email.message import EmailMessage
from email.utils import make_msgid
import smtplib
import os
import ssl
import requests
import io
import time

start_time = time.time()

# 配置邮箱信息
email_sender = 'chris@gmail.com'
email_receiver = 'chris@gmail.com'
email_password = 'aaaa aaaa aaaa aaaa'
subject = 'Test run HTML multiple images using URLs'

# 读取指定文件夹内的图片路径
folder_path = r'C:\Users\chris\OneDrive\My Computer\Reddit API\cats\images'
plots = {}
for file_name in os.listdir(folder_path)[:3]:
    file_path = os.path.join(folder_path, file_name)
    plots[file_name] = file_path
    print(f'{file_name}. {file_path}')

# 收集图片数据、类型和CID
imgs = []
for image_name, image_location in plots.items():
    with open(image_location, 'rb') as img:
        image_data = img.read()
        if image_name.endswith('png'):
            image_type = 'png'
        elif image_name.endswith('jpeg') or image_name.endswith('jpg'):
            image_type = 'jpg'
    imgs.append({
        "name": image_name,
        "data": image_data,
        "type": image_type,
        "cid": make_msgid().strip("<>")
    })

# 构建HTML邮件内容，嵌入图片占位符
html = """\
<html><head><title>Plots</title></head>
 <body>
  <h1>Your Plots</h1>
  <p>Dear Victim,</p>
  <p>Here are today's plots.
   <ul>
"""
for img in imgs:
    html += f'    <li><img src="cid:{img["cid"]}" style="max-width: 500px; height: auto;" alt="{img["name"]}" /></li>\n\n'
html += """\
   </ul>
  </p>
  <p>Plot to take over the world!</p>
 </body>
</html>
"""

print('\n\nhtml template:\n\n')
print(html)

# 创建邮件对象并配置内容
msg = EmailMessage()
msg['Subject'] = subject
msg['From'] = email_sender
msg['To'] = email_receiver

msg.set_content(html, subtype="html")

# 将图片添加为邮件关联内容
for img in imgs:
    msg.add_related(
        img["data"], "image", img['type'],
        cid=f'<{img["cid"]}>')

# 发送邮件
context = ssl.create_default_context()
try:
    with smtplib.SMTP_SSL('smtp.gmail.com', 465, context = context) as smtp:
        smtp.login(email_sender, email_password)
        smtp.sendmail(email_sender, email_receiver, msg.as_string())
        print('Email sent successfully')
except Exception as e:
    print(f'Failed to send due to {e}')

end_time = time.time()

print(f'The script runs for {(end_time - start_time)/60} minutes.')

内容的提问来源于stack exchange，提问作者chris nguyen