Do I need separate sending domains for each brand in my app?

Not always. Whether you need separate sending domains depends on how different your brands are and how much you want to isolate reputation, deliverability, and branding.

Use one sending domain if:

• The brands are closely related
• Users expect emails from the same parent company
• You want simpler setup and maintenance
• Email volume is moderate and shared reputation is acceptable

Example:

• notifications.yourcompany.com sending for both Brand A and Brand B

Use separate sending domains if:

• The brands are distinct and should look independent
• You want to isolate deliverability reputation per brand
• One brand may send much more mail or risk spam complaints
• Different brands have different email content, audiences, or compliance needs

Example:

• brand-a.mail.yourcompany.com
• brand-b.mail.yourcompany.com

Best practice for most apps

A common pattern is:

• One root sending infrastructure
• Separate subdomains per brand or product
• Shared technical setup, but separate reputation and clearer branding

This gives you isolation without the operational burden of completely separate domains.

Practical rule of thumb

• 1 brand / 1 company: one sending domain is usually fine
• Multiple visible brands: separate subdomains are usually better
• High email volume or higher risk: separate domains/subdomains recommended

Also consider

Even if you use one sending domain, you should still make sure:

• From names match the brand
• DKIM/SPF/DMARC are configured correctly
• Unsubscribe and support links are brand-appropriate
• Email content is clearly tied to the brand the user signed up for

If you want, I can suggest a domain setup based on your specific app structure, like whether you have one parent company with multiple products or fully separate brands.