Marketing emails not sending due to unexpected SMTP configuration errors

deepacreator
Fri, 20 Jun 2025 09:52:00 +0000

Check your domain’s DMARC policy as well. If you recently updated DKIM and have a strict DMARC policy (p=reject or p=quarantine), failed DKIM validation will cause immediate delivery failures. You can temporarily set DMARC to p=none while troubleshooting. Also, verify you’re not hitting any sending limits - HubSpot has daily send limits per domain that might be triggered if you had retry attempts piling up during the DNS transition period.