DomainCanary

DomainCanary checks the email authentication records your domain publishes in DNS and shows you what to fix. Ask for a check to see your live DMARC, SPF and DKIM records, plain-English explanations of any problems, and the exact records to publish. Tell us which services send your email and we'll build one SPF record for all of them, tracking your DNS lookups against the limit of ten. You can also paste a bounce message to see why a server refused your mail, what to change and when the bounces will stop. Or upload a DMARC aggregate report to see which senders passed and failed.

Use this whenever mail bounces or fails authentication. We read public DNS and the text and files you give us, with no access to your mailbox or server logs. We never change your DNS, so you publish the records yourself at your DNS host. You don't need an account, and we never write anything you check to a database or a log. Every answer links to the matching page on domaincanary.com.