Python exchangelib how to get today's unread mail list?

I'm trying to get only today's unread mail list by using Python exchanglib library. My code is like this below:

from exchangelib import Account,Credentials
import time

def connect_mail(username, pwd, addr):
    credentials = Credentials(username=username, password=pwd)
    account = Account(addr, credentials=credentials, autodiscover=True)
    return account

def get_unread_mail(account):
    res = account.inbox.filter(is_read=False)
    return res

a = connect_mail(username, pwd, addr)   
unread_mail_list = get_unread_mail(a)
current_date = time.strftime("%Y%m%d", time.localtime()) 
curr_mail_list = []
for mail in unread_mail_list :
    if str(mail.datetime_received)[:10].replace('-','') == current_date:
        curr_mail_list .append(mail)

This code may work , but actually this code will run for a long time cause i've a plenty of unread mails in my inbox.

And then I wanna solve it by using .filter().

Code is like this:

from exchangelib import EWSDate, EWSDateTime

def today_mail(account):
    today = EWSDate.today()
    mails = account.inbox.all().filter(start__gte=today)
    return mails

Or:

def today_mail(account):
    start = account.default_timezone.localize(EWSDateTime(2020, 6, 29))
    end = account.default_timezone.localize(EWSDateTime(2020, 7, 1))
    mails = account.inbox.all().filter(start__range=(start,end))

But unfortunately, it doesn't work.

Can anyone give me a hand on this? Thanks!