Email matching fails when addresses contain uppercase letters

[Franck-Patissier-Orbeet]

Module

fetchmail_attach_from_folder

Bug Description

Emails containing uppercase letters in the address are not linked to partner records.

Steps to reproduce the issue

Configure a folder to attach emails to partners based on the email field.

Save a partner with an email address in uppercase (Name.SURNAME@Domain.com) and/or another in lowercase (name.surname@domain.com).

Drop an email into the monitored folder with the same address but in a different case (e.g., Name.SURNAME@Domain.com).

Notice that no match is found, even though the address exists in Odoo.

Expected Behavior

The matching should be case-insensitive, so that:

NAME.SURNAME@DOMAIN.COM
name.surname@domain.com
Name.SURNAME@Domain.com
are all treated as the same address.

Additional Context

Odoo version: 18
IMAP/Email server: Gmail

This issue prevents emails with uppercase/mixed-case addresses from being attached to the correct partners, even when the address exists in Odoo.

[aviralgarg05]

I would like to solve the issue for hacktoberfest