When setting up email sending, one of the most important decisions is whether to send from your root domain (e.g., example.com) or a subdomain (e.g., mail.example.com). We strongly recommend using a subdomain for all email sending.
Email reputation is tied to the domain you send from. If something goes wrong—high bounce rates, spam complaints, or a misconfigured campaign—only the subdomain’s reputation is affected.
Scenario
Root Domain Impact
Subdomain Impact
Spam complaints spike
Your entire domain flagged
Only subdomain flagged
Blocklist addition
All email affected
Only subdomain email affected
Recovery time
Weeks to months
Days to weeks
With a subdomain, your root domain remains pristine for critical communications like password resets, invoices, and personal emails.
Different types of email have different engagement patterns. Marketing emails typically have lower open rates than transactional emails. Mixing them can drag down your overall reputation.Recommended subdomain structure:
A new subdomain starts with a neutral reputation. This is actually a good recovery strategy—create a new subdomain and warm it up properly while the root domain recovers.
Partially. Mailbox providers consider domain relationships, but subdomains build their own reputation over time. A compromised root domain can affect subdomain deliverability initially.
