退回邮件检查

如何解决退回邮件检查

我正在编写一个程序，该程序检查哪些电子邮件地址被退回（未送达），并在Python中生成一个列表。但是到目前为止，我仅在收件箱的第一页中收到退回的电子邮件（从我从代码中了解的内容）。这是我到目前为止的内容：

inbox = {}

for item in items:

# getting email content
resp,data = M.fetch(item,"(RFC822)")
email_content = data[0][1]

msg = email.message_from_bytes(email_content)
content_list = msg.as_bytes().decode(encoding='UTF-8').split('\n')

# retrieve email address sent out
for cl in content_list:
    if cl.startswith('To: '):
        inbox[cl.replace("To: ",'').strip()] = 1
    #print(cl) this prints out the sent email addresses

fail_content = ['Delivery Status Notification (Failure)','Undeliverable:','DELIVERY FAILURE:','Returned mail:','Undelivered Mail Returned to Sender']

# check Inbox
M.select('INBOX')
resp,items = M.search(None,"All")
items = items[0].split()
#print(items) prints out the number of inbox emails

for item in items:
resp,"(RFC822)")
email_content = data[0][1]
msg = email.message_from_bytes(email_content)

# check for all possible fail content
for fc in fail_content:
    if fc in msg['Subject']:
        # get email content
        content_list = msg.as_bytes().decode(encoding='UTF-8')
        # find its sender
        for eo in inbox:
            if eo in content_list:
                inbox[eo] = 0

print(inbox)