Do I need separate IPs as well?

If volume justifies dedicated IPs, yes. Below ~50k/month/provider, shared IPs from your ESP are usually fine — the subdomain split is what matters.

All guides

Routing

Subdomain strategy for transactional vs marketing mail

Reputation is per-domain. Sending transactional, marketing, and corporate mail from the same domain means a single bad campaign can suppress password resets.

Standard layout

Root example.com for corporate / human mail. mail.example.com or m.example.com for marketing. tx.example.com or notify.example.com for transactional. Each subdomain has its own SPF/DKIM/DMARC posture.

Why subdomains and not separate domains

Separate domains lose brand recognition, hurt opens, and trigger phishing filters. Subdomains keep the brand intact while compartmentalising reputation.

Root DMARC stays strict

Set the root domain DMARC to p=reject early. Subdomains use sp= or their own _dmarc record. This prevents impersonation of your apex while giving marketing room to ramp policy more slowly.

Frequently asked questions

Do I need separate IPs as well?: If volume justifies dedicated IPs, yes. Below ~50k/month/provider, shared IPs from your ESP are usually fine — the subdomain split is what matters.