1. Company Configuration:

   • Make sure each company in Odoo has its own domain set up. Go to "Settings" > "General Settings" > "Companies" and set the "Domain" field for each company to their respective domain.

2. Email Templates:

   • Customize email templates for each company. You can do this by editing the email templates and using placeholders for dynamic data like company name, website URL, etc.

3. Outgoing Email Server:

   • Configure an outgoing email server for each company. Go to "Settings" > "Technical" > "Email" > "Outgoing Mail Servers" and create a separate outgoing email server for each company. Configure the SMTP settings and set the "Alias Domain" to the domain of the respective company.

4. Domains and Aliases:

   • For each company, set up email aliases associated with their domain. Go to "Settings" > "General Settings" > "Email" > "Aliases" and create email aliases for each company's domain. This helps Odoo identify which company to associate emails with.

5. Access Rights:

   • Make sure users are assigned to the correct company. Each user should have access to the company they belong to. This ensures that the correct company's settings, templates, and email servers are used.

6. Invoicing and Document Settings:

   • Set up the invoicing and document settings (like purchase orders, sales orders, etc.) for each company. Make sure that each document's sender company is correctly configured.

7. Testing:

   • Test the setup by sending test emails from different companies and verifying that they are sent using the correct email server and templates.

8. DNS Configuration:

   • Ensure that the DNS records for each domain are properly set up. MX records should point to the correct email servers.

9. SSL Certificates:

   • If you're using HTTPS, make sure you have SSL certificates properly configured for each domain.

Hi, 

You can see following for this:

https://youtu.be/GkNgc-fZO-I

Hope it helps,

Thanks