[BUG] Applicants do not receive emails

[PeterSchwarzHPI]

Impacted versions:
15.0 latest

Steps to reproduce:

1. Create a Job and add an mail template to the initial stage (so that an automatic email is sent when an application is created).
2. Create an application (e.g. via Form). Now the automatic email should be send.
3. Try to send a new e-mail via mail composer.

Current behavior:
The applicant will not receive an email, because odoo does not add the applicant as a recipient.

Expected behavior:
The applicant should receive an email and should be added as a recipient before.

Additional notes:
I think the issue is a combination of the facts that in general private addresses are filtered out in the mail composer but in hr_recruitment module the applicant's res.partner is created as a private address in the "_message_post_after_hook" method.

[1moere1]

Did someone solve this issue? I am not sure where to tweak it to also allow private address mailing in hr_recruiting module from full composer