Creating a text file by searching a string in Outlook inbox（including group inbox)

Question

I'm using Microsoft 365. I am new in Python and my boss asked me to write a Python code which will search a string in my Outlook folder (including inbox and several groups) and create a text file of that mail if that string is present. I did the searching of a specific string in mail subject but did not know how to do the rest of the code. I am trying the following ways to search a string in mail subject.

# Find last mail containing a certain subject in the 'sent items'
# Open the mail with reply all function
#
import os
import win32com.client as win32


# nice information to work with windows
# excel and so on
# https://pbpython.com/windows-com.html
# Complete documentation here: https://docs.microsoft.com/en-us/office/vba/api/outlook.mailitem.move
os.startfile("outlook")
# Outlook MAPI
outlook = win32.gencache.EnsureDispatch("Outlook.Application").GetNamespace("MAPI")
# outlook = win32.Dispatch("Outlook.Application")


# Here the name of the folders
# 3 = Drafts
# 4 = Outbox
# 5 = Sent items
# 6 = Inbox
sentItems = outlook.GetDefaultFolder(5) # "6" refers to the index of a folder - in this case,
# 6 the inbox. You can change that number to reference any other folder

messages_sent = sentItems.Items

found = False
message_subject_to_find = 'Hello'
subject_found = ''


for message in messages_sent: 
    # print('Message class: {}'.format(message.Class))
    # print('Message subject: {}'.format(message.Subject.encode("utf-8")))
    # Message class 43 -> mail
    # if message.Class == 43:
        if message_subject_to_find in message.Subject:
            subject_found = message.Subject
            found = True
            message.ReplyAll().Display()
            break

if found:
  print('Done for this item !! -> {}'.format(subject_found))
else:
  print('Subject not found')