Bumping this up. I'm also confused. 

Echoing the "Is the 'contacts app' not automatically syncing and communicating with the 'email marketing', 'sms marketing' and other apps? Surely not...." sentiment 

Before I add in a million contacts in the contacts app and not be able to pull them into my mailing list...let's get an answer on this pls odoo!

I'm also concerned by this. It seems simply impossible that a basic internal connection of this nature might be missing. Surely I am missing something here???

Is the 'contacts app' not automatically syncing and communicating with the 'email marketing', 'sms marketing' and other apps? Surely not....

Anyone had a decent reply to this? 
I'm also setting up a newsletter but I think it's rather strange to have to duplicate al my contacts in a separate list.

So is there a definitive solution for this, because we are in the same phase right now and would really like to only have to input a contact once in the system.
Or @odoo is there a reason why this is not possible by default?

Please enlighten us.

Anyone from Odoo, do you have a response to this - it is completely odd to not have a way to either 1-click add contact to a mailing list OR when I start to type an email in Mailing List Contacts it finds the contact in my Contact module....I am clearly missing something here cause this is a VERY basic feature for CRM and marketing systems, so it has to be something I (and clearly several others) are doing wrong or a configuration we haven't toggled on/off...someone from Odoo or an Odoo developer, PLEASE HELP! What are we doing wrong here? 

- You can create server actions (one per mailinglist) and add contextual action
- then switch to "Contacts" ->list view, select the desired contacts and execute the action under "Actions":

https://apps.odoo.com/apps/modules/16.0/mass_mailing_partner

There is a free OCA Module for this, but it will only work if you are hosting On-premise or Odoo.SH.

Disclaimer: I have not tested this module yet, but I will as soon as it is migrated and available on v17. 

Hi,

You can add mailing list contacts as existing contacts or by creating a new contact. You can choose the recipients field as contacts and can add specific conditions while creating a mailing.

Regards