---
title: "SPF (Sender Policy Framework) — monitoring glossary"
description: "Sender Policy Framework (SPF) is an email authentication standard that publishes the list of IP addresses authorised to send mail on behalf of a domain.…"
canonical: "https://lemwatch.com/glossary/spf"
source: "https://lemwatch.com"
---

# SPF (Sender Policy Framework)

> Sender Policy Framework (SPF) is an email authentication standard that publishes the list of IP addresses authorised to send mail on behalf of a domain. Mailbox providers reject mail from unlisted IPs.

## Definition

 SPF is published as a single DNS TXT record at the apex of the domain, listing IPs and includes (other domains' SPF policies that should be merged in). It has hard limits — no more than 10 DNS lookups during evaluation — that surprisingly many large senders quietly violate.

 SPF alone is fragile: it breaks on email forwarding (the forwarder's IP is not on the original sender's SPF list). It is therefore always paired with DKIM and DMARC for a complete authentication stack.

## Why it matters

 Missing or misconfigured SPF causes legitimate marketing and transactional email to land in spam, killing conversion rates and customer notifications. It is also a prerequisite for DMARC enforcement.

 See it in the product: [Email deliverability](https://lemwatch.com/features).


## Related

- [Monitoring glossary](https://lemwatch.com/glossary)
- [DMARC](https://lemwatch.com/glossary/dmarc)
- [DKIM](https://lemwatch.com/glossary/dkim)
- [DNS](https://lemwatch.com/glossary/dns)
- [All monitoring checks](https://lemwatch.com/features)
- [SSL/TLS (Secure Sockets Layer / Transport Layer Security)](https://lemwatch.com/glossary/ssl)
- [Service Level Objective (SLO)](https://lemwatch.com/glossary/slo)