How do CNAME or tracking domain errors trigger bounces?

CNAME and tracking domain errors can break email delivery:

How tracking domains work:

ESP provides tracking domain for links. You create CNAME pointing to ESP. Links in email use your branded domain. ESP handles click tracking and redirect.

What can go wrong:

CNAME not configured: Your domain does not resolve to ESP. CNAME deleted: Was working, now broken. ESP endpoint changed: CNAME target no longer valid. SSL certificate mismatch: HTTPS fails on custom domain.

Impact on delivery:

Broken links may trigger spam filters. Unresolvable domains look suspicious. Content scanning fails on broken URLs.

Prevention:

Monitor tracking domain health. Test links before sending. Update CNAMEs when ESP changes endpoints.

Tracking domains are your branded harbor markers. Keep them properly maintained.