What the message looks like
550 5.7.23 SPF validation failed550 5.7.23 Message rejected due to SPF policy
What it means
The receiving server checked the sender's SPF record and the email came from a server that isn't on it. The domain's SPF record told receivers to reject mail that fails, so it did. The standard name for this status is "SPF validation failed".
SPF is a DNS record that lists which servers are allowed to send email for a domain.
Common causes
- A new email service, newsletter tool or CRM sends as your domain but hasn't been added to your SPF record.
- The SPF record has a typo, or there's more than one SPF record for the domain, which makes both invalid.
- The record needs more than 10 DNS lookups to check, which makes it fail.
- The email was forwarded by a server that changed the route without rewriting the sender address.
If you're the recipient
There's nothing to change on your side. Let the sender know their emails are being rejected.
If you're the sender
Check your domain's SPF record with an SPF checker. Make sure every service that sends as your domain is included, that there's only one record starting with v=spf1, and that it stays within the 10 lookup limit. Setting up DKIM and DMARC as well makes delivery more reliable.
If you use addy.io
When addy.io forwards an email, it sends it from its own servers using a rewritten sender address, so forwarding doesn't break SPF for your inbox provider. If you use your own domain with addy.io, make sure its SPF record includes addy.io as shown on your Domains page.