The mark as read button was not working for mail failure. More than that,
we wanted a functionnality to be able to massively mark mail failure as canceled,
especially to be able to clean databases from failure after migration.
Task: #1860054
PR: #25622
When a mail is in failure state, a red envelope appears next to the message
in a thread but it was difficult to send the mail again.
This tasks will allow users to send mail again easily, or mark notification
as cancelled if the user want to ignore this failure.
A notification will appear in sender systray while mail are in failure.
Task: #46158
PR: #24628
qsm-odoo