Should SPF records match the 'From:' address or the Return-Path domain when sending from Marketo?

Summary

All sources, including documentation, experts, and email marketers, agree that SPF records should authenticate the Return-Path domain (also known as the MAIL FROM or envelope sender), used during the SMTP transaction. The 'From:' address is authenticated via DKIM and DMARC, and generally doesn't need its own SPF record. Properly configuring SPF for the Return-Path and DKIM/DMARC for the 'From:' address is crucial for email deliverability, particularly when using different domains for each.

Key findings

  • SPF Authenticates Return-Path: SPF is designed to authenticate the Return-Path domain, which is used during the SMTP transaction.
  • DKIM/DMARC for 'From:': DKIM and DMARC are responsible for authenticating the 'From:' address.
  • No SPF for 'From:' Needed: Generally, it's not necessary to publish an SPF record for the domain used in the user-visible 'From:' address.
  • Marketo Return-Path Data: Marketo includes data (Munchkin ID, campaign details) in its Return-Path address, which should be considered during SPF configuration.
  • SPF and Forgery: The primary function of SPF is to prevent sender address forgery.

Key considerations

  • Return-Path Configuration: Focus SPF configuration on authorizing the sending sources for the Return-Path domain.
  • DKIM/DMARC Setup: Ensure correct DKIM and DMARC configuration to authenticate the 'From:' address, especially when it differs from the Return-Path domain.
  • Deliverability Impact: Incorrect or incomplete SPF and DKIM/DMARC setups can significantly impact email deliverability.
  • Bounce Handling: The Return-Path domain is used for handling bounces and other delivery-related notifications.
  • Comprehensive Authentication: SPF, DKIM, and DMARC must work together to provide a comprehensive email authentication strategy.

What email marketers say
8Marketer opinions

The consensus is that SPF records should align with the Return-Path domain (also known as the MAIL FROM or envelope sender) rather than the 'From:' address. SPF authenticates the sending server for the Return-Path domain, which is used for bounces and delivery-related communication. While the 'From:' address is important for branding and user perception, it is authenticated through DKIM and DMARC. Using different domains for the Return-Path and 'From:' address requires proper configuration of DKIM and DMARC to avoid deliverability issues.

Key opinions

  • SPF and Return-Path: SPF authenticates the domain used in the Return-Path (MAIL FROM).
  • From: Address Authentication: The 'From:' address is authenticated through DKIM and DMARC, not directly by SPF.
  • DMARC Alignment: DMARC uses SPF and DKIM to verify the 'From:' domain.
  • Marketo Return-Path Data: Marketo includes data in the Return-Path address (Munchkin ID, campaign details).
  • SPF Purpose: SPF's primary goal is to prevent sender address forgery.

Key considerations

  • Domain Alignment: If the 'From:' and Return-Path domains differ, ensure proper DKIM and DMARC setup.
  • Deliverability Impact: Incorrect SPF configuration can lead to deliverability problems.
  • Bounce Handling: The Return-Path is used for bounce and delivery notifications.
  • Authentication Standard: SPF, DKIM, and DMARC work together to provide comprehensive email authentication.
  • Marketo Specifics: Consider the data Marketo includes in its Return-Path addresses when configuring SPF.
Marketer view

Email marketer from Mailjet answers that SPF should align with the domain used in the Return-Path, as this is the address used for bounces and delivery-related communications. The 'From:' address is a separate consideration for sender reputation and branding.

December 2024 - Mailjet
Marketer view

Email marketer from Email on Acid notes that SPF is used to authenticate the envelope sender (Return-Path), so the SPF record must include the sending sources authorized to send mail for that domain. DKIM can then be used to verify the 'From' domain. DMARC ties it all together.

August 2021 - Email on Acid
Marketer view

Email marketer from SendGrid explains that SPF is designed to prevent sender address forgery. It authenticates the server sending email on behalf of your domain, which is related to the Return-Path, not directly the 'From:' address.

March 2023 - SendGrid
Marketer view

Email marketer from Email Geeks shares that the Return Path email addresses for Marketo pass a lot of data back such as Munchkin ID, smart campaign, run step, record ID, etc.

November 2021 - Email Geeks
Marketer view

Email marketer from Litmus responds that SPF authenticates the Return-Path domain. DMARC builds upon SPF and DKIM to verify the 'From:' domain and specify how to handle emails that fail authentication.

August 2021 - Litmus
Marketer view

Email marketer from Stack Overflow answers that SPF needs to authenticate the domain in the 'MAIL FROM' (Return-Path). The 'From:' domain is important for other checks such as DMARC. DKIM is needed for alignment between 'From:' and authenticated domains.

May 2021 - Stack Overflow
Marketer view

Email marketer from GlockApps shares that it's crucial for SPF to align with the Return-Path domain, as this is what receiving mail servers check for authentication. Using a different domain in the 'From:' address than in the Return-Path can cause deliverability issues if not handled correctly with DKIM and DMARC.

July 2021 - GlockApps
Marketer view

Email marketer from Reddit suggests that SPF records should be set up to authorize the mail server used by Marketo to send emails on behalf of the domain in the Return-Path, even if the 'From:' address uses a different domain. DMARC can then align the 'From:' domain using DKIM.

June 2021 - Reddit

What the experts say
3Expert opinions

The expert consensus is that SPF records should align with the Return-Path domain, also known as the envelope sender, as this is the address authenticated during the SMTP transaction. It's generally unnecessary to publish an SPF record for the domain in the user-visible 'From:' address. The authentication of the 'From:' address is handled by DKIM and DMARC.

Key opinions

  • SPF and Return-Path: SPF authenticates the Return-Path domain (envelope sender).
  • From: Address Authentication: The 'From:' address is handled by DKIM and DMARC.
  • No SPF for From:: Generally, no SPF record is needed for the domain in the 'From:' address.
  • SMTP Transaction: The Return-Path address is used during the SMTP transaction.

Key considerations

  • Domain Alignment: Focus SPF configuration on the Return-Path domain.
  • DKIM/DMARC: Ensure DKIM and DMARC are properly configured to authenticate the 'From:' address.
  • Deliverability: Proper configuration is crucial for email deliverability.
Expert view

Expert from Word to the Wise explains that SPF is related to the Return-Path (the envelope sender). The domain in the 'From:' header is handled by DKIM and DMARC.

August 2024 - Word to the Wise
Expert view

Expert from Email Geeks explains that the SPF record should be for the domain used in the Return Path, not necessarily the user-visible From: address. Also you generally don't need to publish a SPF record for the domain in your user visible From.

November 2024 - Email Geeks
Expert view

Expert from Email Geeks explains that the Return Path is the address used during the SMTP transaction and is authenticated by SPF. It's not the reply-to address.

August 2023 - Email Geeks

What the documentation says
3Technical articles

Official documentation consistently states that SPF records should authenticate the MAIL FROM address, also known as the envelope sender or Return-Path. This address is used during the SMTP transaction. The 'From:' header address, which is what the user sees, is authenticated by DMARC in conjunction with DKIM, not by SPF.

Key findings

  • SPF Usage: SPF authenticates the MAIL FROM (Return-Path) address.
  • SMTP Transaction: SPF is used during the SMTP transaction to verify the sender.
  • From: Address Handling: The 'From:' address is authenticated by DMARC and DKIM.
  • MAIL FROM Identity: SPF checks are performed on the Return-Path domain during email delivery.

Key considerations

  • Return-Path Focus: Ensure SPF records accurately reflect authorized sending sources for the Return-Path domain.
  • DMARC and DKIM Setup: Proper DMARC and DKIM configuration is essential for authenticating the 'From:' address and ensuring deliverability.
  • Authentication Hierarchy: Understand the roles of SPF, DKIM, and DMARC in the overall email authentication process.
Technical article

Documentation from DMARC.org shares that SPF authenticates the domain used in the Return-Path (also called MAIL FROM or envelope sender). This is distinct from the 'From:' header address, which is covered by DMARC in conjunction with DKIM.

February 2024 - DMARC.org
Technical article

Documentation from RFC Editor defines SPF as authenticating the MAIL FROM identity, emphasizing that it is the Return-Path domain that undergoes SPF checks during email delivery.

April 2022 - RFC Editor
Technical article

Documentation from Microsoft Learn explains that SPF records should authenticate the MAIL FROM address (also known as the envelope sender or Return-Path), which is used during the SMTP transaction, not the 'From:' address displayed to the user.

September 2024 - Microsoft Learn