[DOCS] Working with BCC recipients

Integrators have to be aware of a problem when sending emails to BCC
recipients. This patch documents the problem and offers a solution
as well as links to the TYPO3 Core API as well as Symfony Docs.

Resolves: #92354
Releases: main, 11.5
Change-Id: Ia1594d8f8c93dfa5c4d58e12d13e61aa350ea9d0
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/73697


Tested-by: core-ci <typo3@b13.com>
Tested-by: Colin Findeisen <colin.findeisen@tritum.de>
Tested-by: waldhacker <hello@waldhacker.dev>
Reviewed-by: Oliver Hader <oliver.hader@typo3.org>
Reviewed-by: Colin Findeisen <colin.findeisen@tritum.de>
Reviewed-by: Elias Häußler <e.haeussler@familie-redlich.de>
Reviewed-by: waldhacker <hello@waldhacker.dev>