Summary
When an ESP uses its own domain for the Return-Path, SPF authentication primarily relies on the Return-Path domain. While the 'From' domain's SPF is less critical for initial authentication, it still impacts email deliverability as a reputation signal and for DMARC alignment. Proper DMARC configuration, through SPF or DKIM of the 'From' domain, is essential for passing DMARC checks and improving deliverability. Setting the correct SPF record on the Return-Path and implementing a DMARC record with strict alignment are crucial for a strong authentication posture and preventing spoofing.
Key findings
- Return-Path SPF is Key: SPF authentication for the Return-Path domain is most critical for deliverability when the ESP uses its own domain.
- 'From' Domain as Reputation Signal: The 'From' domain SPF record functions as a reputation signal, impacting how receiving servers handle the email.
- DMARC Alignment is Essential: DMARC alignment through SPF or DKIM of the 'From' domain is crucial for passing DMARC checks and improving deliverability.
- ESP Onboarding & SPF: ESPs often instruct clients to set up SPF records for their 'From' domains for compatibility and in case DMARC is implemented.
Key considerations
- Prioritize Return-Path SPF: Ensure the ESP's Return-Path domain has a correctly configured SPF record.
- Implement DMARC: Implement a DMARC policy that aligns with the 'From' domain using SPF or DKIM.
- Monitor 'From' Domain Reputation: Despite the Return-Path being primary, monitor the reputation of your 'From' domain.
- Strict DMARC setup: Make sure to properly set up SPF records using the correct syntax, and using DMARC alignment if you send on behalf of other emails, or your own.
What email marketers say
9 marketer opinions
When an Email Service Provider (ESP) uses its own domain for the Return-Path, the SPF record of the 'From' domain becomes less critical for initial email authentication. The Return-Path's SPF record is the primary factor for deliverability. However, the 'From' domain SPF record still influences email deliverability as it serves as a reputation marker and is important for DMARC alignment. Ensuring DMARC passes through either SPF or DKIM is critical for optimal deliverability.
Key opinions
- Return-Path SPF: The SPF record of the Return-Path domain (controlled by the ESP) is most critical for initial email authentication and deliverability.
- 'From' Domain Reputation: The 'From' domain's SPF record acts as a reputation signal, influencing how receiving mail servers handle the email.
- DMARC Alignment: The 'From' domain's authentication, whether through SPF or DKIM, is essential for DMARC alignment, which significantly impacts deliverability.
- ESP Onboarding: ESPs often instruct clients to add SPF records for the 'From' domain, primarily for legacy reasons and potential DMARC considerations.
Key considerations
- Monitor Reputation: Monitor the reputation of your 'From' domain, even when the ESP handles Return-Path SPF.
- DMARC Configuration: Ensure proper DMARC configuration, aligning either SPF or DKIM with the 'From' domain.
- ESP Requirements: Adhere to any SPF record requirements specified by your ESP, even if they use their own Return-Path.
- Domain Validation: It's important to validate your From domain, as services like Google validate email with DMARC becoming more important.
Marketer view
Email marketer from StackExchange user explains that the Return-Path gets SPF checked which is most important for deliverability but the From domain helps improve reputation.
5 Oct 2023 - StackExchange
Marketer view
Marketer from Email Geeks shares that often ESP onboarding will instruct clients to add an SPF lookup to the sender’s “from” domain just in case (because of previous SPF/sender-id standards), but the ESP will be using their own domain for the return-path, which has its own SPF record already and so the “from” domain record doesn’t actually have an impact one way or the other.
19 Oct 2022 - Email Geeks
What the experts say
2 expert opinions
When an ESP controls the Return-Path, ensuring its authentication is paramount. While the 'From' domain SPF record becomes less critical for initial authentication, setting a correct SPF record on the Return-Path and DMARC record using adkim=s and aspf=s for strict alignment is crucial.
Key opinions
- Return-Path Authentication: Successful Return-Path authentication is the most important factor for email delivery when an ESP manages it.
- Strict DMARC Alignment: Implement a DMARC record with strict alignment (adkim=s, aspf=s) to ensure mailboxes accept mail that aligns DKIM and SPF results with the 'From' domain.
Key considerations
- Return-Path SPF Record: Ensure a correct SPF record is set on the Return-Path/envelope from domain.
- DMARC Implementation: Carefully implement DMARC to enforce alignment between DKIM, SPF, and the 'From' domain.
Expert view
Expert from Spam Resource explains that it will be more difficult to be sure where to put SPF records now, if you want to get really technical and you are an e-mail marketer sending on behalf of someone else you need to set the correct SPF record on the Return-Path/envelope from domain, and you will want to set up a DMARC record that uses adkim=s and aspf=s to tell receiving mailboxes they should only accept mail that aligns the DKIM and SPF results with the from domain.
16 Aug 2024 - Spam Resource
Expert view
Expert from Word to the Wise responds that what matters most is that the Return-Path passes authentication, which is typically controlled by the ESP. The 'From' domain reputation is less important when the Return-Path passes authentication.
10 May 2022 - Word to the Wise
What the documentation says
5 technical articles
When an ESP uses its own domain for the Return-Path, SPF authentication is primarily based on the Return-Path domain. The 'From' domain SPF becomes less relevant for initial authentication, but DMARC alignment, achieved through either SPF or DKIM, remains crucial. Configuring SPF, DKIM, and DMARC records for the primary email domain is recommended to prevent spoofing. Even if the 'From' domain fails SPF, the message can still pass DMARC if the Return-Path passes SPF and DKIM aligns, depending on the DMARC policy.
Key findings
- Return-Path Priority: SPF authenticates the 'Return-Path' domain; its SPF record is paramount when an ESP uses its own domain.
- DMARC Alignment Importance: DMARC alignment, via SPF or DKIM, of the 'From' domain is vital for overall authentication and deliverability.
- 'From' Domain Reputation: The 'From' domain's SPF can still be considered for reputation and DMARC alignment, even if not used for initial SPF verification.
- Spoofing Prevention: Configuring SPF, DKIM, and DMARC is recommended to prevent email spoofing.
Key considerations
- Return-Path SPF Setup: Ensure that the ESP's Return-Path domain has a correctly configured SPF record.
- DMARC Policy: Implement and maintain a DMARC policy to leverage SPF and DKIM for 'From' domain authentication.
- 'From' Domain Configuration: Although less critical for initial authentication, configure SPF, DKIM, and DMARC for the 'From' domain to prevent spoofing and maintain reputation.
Technical article
Documentation from SparkPost explains that the Return-Path domain's SPF is checked for initial SPF verification. If the ESP uses its domain, that SPF record must pass. The 'From' domain's SPF may still be considered for reputation and DMARC alignment.
31 Jul 2021 - SparkPost
Technical article
Documentation from DMARC.org explains that SPF authenticates the 'Return-Path' domain. If an ESP uses its own 'Return-Path', the 'From' domain SPF is less relevant for initial authentication. DMARC alignment, however, can tie the 'From' domain to the authentication results.
3 Feb 2023 - DMARC.org
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