我找不到一种方法来比较python中的电子邮件正文，因为一些电子邮件最后包含额外的许可消息

import email
import difflib

msg1 = email.message_from_string(email1)  # email1为第一个电子邮件的字符串表示
msg2 = email.message_from_string(email2)  # email2为第二个电子邮件的字符串表示

body1 = ""
if msg1.is_multipart():
    for part in msg1.walk():
        if part.get_content_type() == "text/plain":
            body1 = part.get_payload(decode=True).decode()
else:
    body1 = msg1.get_payload(decode=True).decode()

body2 = ""
if msg2.is_multipart():
    for part in msg2.walk():
        if part.get_content_type() == "text/plain":
            body2 = part.get_payload(decode=True).decode()
else:
    body2 = msg2.get_payload(decode=True).decode()

diff = difflib.ndiff(body1.splitlines(), body2.splitlines())
changes = [line for line in diff if line.startswith("+ ") or line.startswith("- ")]

if len(changes) == 0:
    print("电子邮件正文相同")
else:
    print("电子邮件正文不同")
    for change in changes:
        print(change)