Should I use subdomains for different email streams (marketing vs. transactional)?

Using subdomains to separate email streams is a widely recommended practice. mail.yourdomain.com for transactional, news.yourdomain.com for marketing, and alerts.yourdomain.com for product notifications. Each builds its own reputation while keeping your brand visible.

The primary benefit is reputation isolation. If an aggressive marketing campaign triggers complaints, it won't affect your transactional email delivery. Password resets and order confirmations continue reaching inboxes while you address the marketing issue.

Subdomains inherit some trust from the parent domain but are evaluated somewhat independently. A new subdomain doesn't start from zero; it benefits from the root domain's age and history while building its own sending reputation.

Different ships, same fleet. They fly the company flag but sail their own routes, so one running aground doesn't block the others.