Hello, 

In standard Odoo, multi-language behavior like Email Templates is not fully supported in the Email Marketing app.

For marketing campaigns, the usual approach is to create separate mailings per language and target the appropriate audience using filters (e.g., customer language).

However, with some customization, it is possible to achieve dynamic multi-language rendering similar to templates, but this is not available out of the box.

Hope this works for you! If you need any help implementing this or want a more optimized approach, feel free to reach out for further discussion

Regards,

Zehntech Technologies Inc.

santosh.sekwadia@zehntech.com

I think no, the Email Marketing app does not support inline translations like the blue-flag translate feature in Settings > Technical > Email > Templates. Mailings in the Email Marketing module are not translatable records by design — the body is rendered as-is, without fetching a per-language version based on partner.lang. 

So out of the box, you need a separate mailing per language.

Practical approach (step by step):

1. Segment your contacts by language — make sure each contact/recipient has the correct Language set on their record.
2. Create one Mailing List per language (e.g. Newsletter - EN, Newsletter - FR, Newsletter - ES), or keep one list and use a domain filter on lang in the mailing's recipients.
3. Duplicate the mailing for each language — build the master mailing once, then use Action > Duplicate and translate the content of each copy.
4. Set the recipient filter on each mailing to target only contacts with the matching lang (e.g. Language = en_US).
5. Schedule/send each mailing separately. They'll share the same campaign if you assign them to one, so reporting stays consolidated.

If you want true single-mailing multilanguage behavior, you have two options:

• Use Marketing Automation with a language condition on the trigger to branch to the right email template (templates do honor ${object.partner_id.lang}).
• Install a third-party module such as Emailing multiple languages on the Odoo Apps Store, which extends mass mailing to send per recipient language — it extends the mass mailing module in order to send a mailing according to the recipient's language.