Definition
A third-party sender delivers mail on behalf of your domain, such as an agency or ESP. Their infrastructure can break SPF unless authorised.
Authorise their IPs or rely on DKIM and aligned DMARC.
Third-party senders add convenience but also authentication risk, since their IPs are not in your SPF record. Authorising them properly and relying on DKIM prevents failures. Keeping a record of all third-party senders helps you monitor them.
Managing Third-Party Sends
Authorise third-party senders in your DNS.
Use DKIM signatures and aligned DMARC.
Why It Matters
Third-party senders add convenience but also authentication risk. Understanding how to authorise them prevents SPF and DMARC failures.
Best Practices
- Authorise third-party senders in your DNS.
- Use DKIM signatures from the third party.
- Confirm DMARC alignment for delegated sends.
- Keep a record of all third-party senders.
- Monitor their sending for compliance.
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Frequently Asked Questions
A service or partner sending mail for your domain. Third-party senders add convenience but also authentication risk, since their IPs are not in your SPF record.
Their IPs are not in your SPF record. Authorising them properly and relying on DKIM prevents failures.
Use DKIM and aligned sending, or add their IPs to SPF. Keeping a record of all third-party senders helps you monitor them.
Unmanaged third-party sends can hurt your reputation. Third-party senders add convenience but also authentication risk, since their IPs are not in your SPF record.
Review their authentication and performance data. Authorising them properly and relying on DKIM prevents failures.