Mailing lists (mail.channel) should not send specific notification emails.
Indeed there can be a lot of recipients and customizing each email can
take time to compute. This leads to posting a message on a mail.channel
being very slow.
It is now possible for a model to customize the notification email
recipients computation. The first use is to ensure that mail.channel
encodes recipients using email_to instead of recipients_ids. This way
less processing is performed on notification emails.
This is a manual cherry-pick of commit d4a1eb4435
that was not forard ported. Mail has indeed evolved since 8.0 and its
forward port was not an easy task.
This commit also includes the fix of mail.channel recipients. All are now
considered as equal and receive a simple notification email. No distinction
is done between partners and users. The notification emails for channels
should be as simple as possible.
Thibault Delavallée
a69c2bab0a