PURPOSE

Be defensive when dealing with email fields, notably when having multi-emails
or email field containing an already-formatted email.

RATIONALE

Two main use case of corner case usage of 'email' fields are tested in this PR
and their support is improved

  * formatted emails: `"Full Name" <email@domain.com>` stored into the 'email'
    field;
  * multi emails: `email1@domain.com, email2@domain.com` stored into a single
    'email' field;

IMPLICATION

Email field is generally managed as "containing a valid email". This means
it is sometimes used as it in 'formataddr' as well as to perform searches or
identification checks. Example of issue: partner 'Raoul' has a formatted email
like "Raoul" <raoul@raoul.fr>. Using 'formataddr' in email_from leads to

  from: "Raoul" <"Raoul" <raoul@raoul.fr>>
  -> which is incorrect (but often dynamically corrected by email servers);

Email field holding multi-emails are not normalized, as current normalize
is done only if the field holds a single email. It means

  * no easy finding based on 'email_normalized', e.g. various tools like
    '_mail_find_partner_from_emails' or 'find_or_create' do not find partners
    based on this email;
  * no exclusion list management;
  * issue with formatting, like

  to: "Raoul" <raoul@raoul.fr,raoul.other@raoul.fr>
  -> which is incorrect (but often dynamically corrected by email servers);

USAGE: OUTGOING EMAILS

Those use cases currently generate faulty outgoing emails. This is valid for
recipients ('email_cc', 'email_to') as well as author ('email_from').

For formatted emails: `email_to` is formatted again based on name and email
which leads to sending emails to `"Full Name" <"Other"<email@domain.com>>`.

Note that multi emails without formatting may work as it leads to email_to
`"Full name" <email1@domain.com,email2@domain.com>`. Some outgoing email
servers correctly send multiple emails. It depends on their fault
tolerance.

USAGE: FIND BASED ON EMAIL (NORMALIZED)

When searching for partners (e.g. using '_mail_find_partner_from_emails' or
'find_or_create') normalized version of input is used.

In case of multi emails sanitize is 'False', as normalization expects a single
email in the field. Therefore no partner is found. In processes that do a
"search or create" (e.g. using a template on a record) this leads to creating
a new partner (or several partners in case of multi emails) each time.

USAGE: OTHER FLOWS

Other flows are build on top of '_mail_find_partner_from_emails' / 'create'
of outgoing emails and are impacted by formatted email / multi email usage.
Those include notably

  * mass_mailing: '_message_get_default_recipients' should be defensive to
    give correct values when creating mailing emails;
  * mass_mailing: faulty emails is based on normalize and multi-emails are
    considered as faulty and ignored;
  * after post hook: '_message_post_after_hook' tries to link messages without
    author (but email_from) with newly-created partners, when partners are
    created from chatter. It is therefore impacted by those corner cases;
  * marketing_automation: built on top of mass_mailing and suffers from the
    same issues;

USAGE: UNICODE

Unicode in emails should be supported. 'formataddr' and IrMailServer notably
received fixes to support unicode. Some check performed on email addresses
fail when unicode is involved, which leads to some emails not being sent
while they could.

USAGE: WRONG EMAIL FORMATTING

With input 'name email@domain.com' (missing chevrons allowing to clearly spot
the email part) 'getaddresses' returns ('', 'name email@domain.com) i.e. the
whole input is considered as being the email.

To improve the heuristic we can add a fallback by recalling 'getadresses'
on the input with spaces replaced by commas when it found only an email and
no name. The new email will be split into sub pairs allowing to find the real
email and various name parts, allowing to make a new name / email pair.

Emails should not contain spaces thus this is coherent with email formation.
This fallback actually comes from a specific code done in '_parse_partner_name'
of Partner model. Supporting it directly at tools level make the behavior
coherent for all models.

SPECIFICATIONS

This PR contains first tests to cover current support of those use cases. Then
we gradually improve support of multi-emails and formatted emails in various
layers of mail code, from mail.mail to mass_mailing or email formatting.

See individual commit for more explanation, each of them solving a specific
issue / use case.

Task-2612945 (Mail: Defensive email formatting)

closes odoo/odoo#74474

Related: odoo/enterprise#41828
Signed-off-by: Thibault Delavallee (tde) <tde@openerp.com>