frappe/frappe/patches/v14_0/copy_mail_data.py

from __future__ import unicode_literals
import frappe


def execute():
	# patch for all Email Account with the flag use_imap
	for email_account in frappe.get_list("Email Account", filters={"enable_incoming": 1, "use_imap": 1}):
		# get all data from Email Account
		doc = frappe.get_doc("Email Account", email_account.name)

		imap_list = [folder.folder_name for folder in doc.imap_folder]
		# and append the old data to the child table
		if doc.uidvalidity or doc.uidnext and "INBOX" not in imap_list:
			doc.append("imap_folder", {
				"folder_name": "INBOX",
				"append_to": doc.append_to,
				"uid_validity": doc.uidvalidity,
				"uidnext": doc.uidnext,
			})

			doc.save()