# -*- coding: koi8-r -*-
import poplib
import base64
import quopri
import re
 
 
def decode_subject(inp):
    found = re.findall(r'=\?([a-zA-Z0-9-]+)\?([bqBQ])\?([a-zA-Z0-9/+=]{4,})={0,2}\?', inp.decode('utf8', 'ignore'))
    try:
        found = list(filter(bool, found[0]))
    except IndexError:
        return inp  # 
    if found[1].upper() == 'B':
        text = base64.b64decode(found[2]).decode(found[0], 'replace')
    else:
        text = quopri.decodestring(found[2]).decode(found[0], 'replace')
    return 'Subject: {}'.format(text)
 
 
server = "pop.mail.ru"
port = "995"
user = "здесь логин"
pasw= 'здесь пароль'
 
 
mServer = poplib.POP3_SSL(server,port)
mServer.user(user)
mServer.pass_(pasw)
print(mServer.stat())
messages = []
senders = []
numMessages = len(mServer.list()[1])
for i in range(numMessages):
    for msg in mServer.top(i+1,0)[1]:
        if msg.startswith(b'Subject'):
            messages.append(msg)
        if msg.startswith(b'Return-path'):
            senders.append(msg)
print (mServer.retr(2)) # 
# mServer.dele(3) #
for i in messages:
    print(decode_subject(i))
 
print('\n')
 
for i in senders:
    print(i)
print (mServer.quit()) # 

 >>> import base64
>>> s = "O3ZhbHVlIFBST0M9IklOUyImZ3Q7LTQuOTMmbHQ7L3ZhbHVlJmd0Ozxicj4KJmx0Oy9wYXJhbWV0"
>>> base64.b64decode(s)
';value PROC="INS"&gt;-4.93&lt;/value&gt;<br>\n&lt;/paramet'