Summary
When configuring DMARC to send reports to an email address outside your primary domain, a specific DNS TXT record is required on the *receiving* domain. This record serves as an explicit authorization, signaling to mailbox providers that the external domain is prepared and willing to receive DMARC aggregate and/or forensic reports from your sending domain. Its primary purpose is to prevent potential abuse, such as mailbombing, by ensuring consent for data transmission.
Key findings
- Authorization TXT Record: A DNS TXT record must be published on the domain that is designated to receive DMARC reports from an external domain. This record explicitly authorizes the receiving domain to collect this data.
- Purpose: The record's main function is to prevent abuse, specifically to avoid mailbombing unsuspecting email addresses with large volumes of DMARC reports.
- RFC 7489 Requirement: The DMARC specification, outlined in RFC 7489 Section 7.1, mandates this authorization for external reporting destinations.
- Internal vs. External: This record is only necessary when the DMARC report recipient email address (specified by rua or ruf tags) belongs to a domain different from the DMARC policy's organizational domain.
- Inconsistent Enforcement: While required, some mailbox providers might still send reports even without this record, leading to inconsistent report delivery if not properly configured.
Key considerations
- Configuration Location: The TXT record must be added to the DNS of the report-receiving domain, not the sending domain with the DMARC record.
- Format: The record typically follows the format <sending-domain>._report._dmarc.<receiving-domain> with a value of v=DMARC1;.
- Third-Party Services: If using a third-party DMARC reporting service, they typically provide instructions for this record or manage it on their end. Understanding the different types of DMARC services is important.
- Ensuring Full Reports: To ensure you receive comprehensive DMARC reports from all ISPs that send them, this authorization record should always be correctly implemented, even if initial reports are received without it.
- Best Practices: Adhering to DMARC best practices, including this authorization, is crucial for effective DMARC setup and robust email security.
What email marketers say
Email marketers often encounter challenges when setting up DMARC reports to be sent to external domains, primarily stemming from the requirement for a specific DNS authorization record on the receiving domain. Their discussions frequently highlight the confusion around why reports might not be delivered consistently or why warning messages appear, even if some reports are received. The consensus leans towards the necessity of this record for reliable and compliant DMARC report reception, particularly when leveraging third-party reporting tools.
Key opinions
- Initial Confusion: Many marketers are initially unsure if the DMARC report recipient email address needs to match the DMARC-configured domain, especially when they receive partial reports despite warnings.
- External Domain Requirement: There's a general understanding that if reports go to an external domain (e.g., a reporting service), a special DNS record on the receiving domain is needed.
- Verification Importance: Marketers recognize that this verification process is crucial for preventing unwanted mail or mailbombing of report recipient inboxes.
- Reliance on Service Providers: Many expect their outsourced DMARC services to handle this technical setup, illustrating a common division of labor.
- Internal Domain Exemption: It's understood that this external verification is not required if the rua address is within the same organizational domain as the DMARC record.
Key considerations
- DNS TXT Record Creation: Marketers need to ensure the correct TXT record, such as example.com._report._dmarc.abc.com with v=DMARC1;, is published on the external receiving domain.
- Comprehensive Reporting: Despite occasional report delivery without the record, full compliance is necessary to guarantee receipt of DMARC reports from all providers.
- DMARC Record Structure: Understanding the function of rua and ruf tags is fundamental for setting up report destinations in the DMARC record.
- Troubleshooting: When reports are missing, the first step should be to verify the presence and correctness of this authorization record on the receiving domain, as highlighted by DuoCircle's guide.
Marketer view
Marketer from Email Geeks asks if the DMARC report recipient email must match the DMARC domain. They observed a warning message about a missing DNS TXT record for authorization when attempting to send reports to an external domain. This issue highlights a common point of confusion for those new to DMARC implementation and external reporting configurations. This scenario often arises when organizations utilize third-party DMARC reporting services or wish to consolidate reports for multiple domains into a single inbox. The warning message directly points to a compliance requirement within the DMARC specification, implying potential data loss if not addressed. Receiving DMARC reports (RUA or RUF) to an email address in a different domain from the sending domain requires specific DNS verification. Without this authorization, recipients (like mailbox providers) may not send reports, as it could be interpreted as an attempt to 'mailbomb' or exploit the reporting mechanism. This is a crucial step for preventing abuse and ensuring data privacy, as outlined in DMARC specifications.
Marketer view
Marketer from Spiceworks Community states that for receiving DMARC reports from an external domain, a specific DNS record must be added to the public DNS of the domain that is *receiving* the reports. This record explicitly grants permission for other domains to send their DMARC data. This acts as a crucial security measure to prevent 'mailbombing,' where malicious actors could flood an unsuspecting email address with DMARC reports by simply listing it in a DMARC record. By requiring explicit authorization, the DMARC standard mitigates this potential for abuse. Without this authorizing TXT record, many email receivers and mailbox providers will rightfully refuse to send DMARC aggregate or forensic reports, as they cannot verify the recipient's willingness to receive them. This protection mechanism ensures privacy and prevents unsolicited data delivery.
What the experts say
Experts universally agree that a DNS TXT record is a mandatory requirement for DMARC aggregate and forensic reports destined for an external domain. This authorization mechanism is a core part of the DMARC specification, primarily designed to prevent potential abuse and ensure that reports are sent only to willing recipients. They emphasize that while some mailbox providers might occasionally send reports without this record, consistent and comprehensive data collection hinges on its correct implementation.
Key opinions
- Mandatory Authorization: The domain receiving DMARC reports must publish a TXT record to announce its readiness to receive reports for an external domain.
- Abuse Prevention: This record is crucial for preventing mailbombing or other abuses of the DMARC reporting mechanism.
- RFC Compliance: Experts direct to RFC 7489, which provides the precise instructions for setting up this authorization record in DNS.
- Report Delivery: While some providers might still send reports without it, compliance ensures consistent delivery from all DMARC-implementing mail servers.
- No DMARC Validation Impact: The authorization record does not affect DMARC authentication validation, but it does affect whether reports are sent.
Key considerations
- Third-Party vs. Self-Managed: If using a third-party reporting service, they typically manage this record. If self-hosting, the domain owner must publish it.
- DNS Record Specifics: The record needed is a TXT record for the report-receiving domain, following a specific subdomain structure (e.g., <sending-domain>._report._dmarc.<receiving-domain>). This is part of the overall DNS configuration for DMARC.
- Varying Strictness: Some DMARC validators might be hit or miss in checking this record, but adhering to the specification is always the best practice for reliability.
- Configuration Problem Indicator: Absence of this record can indicate a configuration problem, which may indirectly affect a domain's reputation with large mailbox providers.
- Impact on Deliverability: While it doesn't directly prevent email delivery, missing reports mean you lack critical data for improving your email deliverability rates and protecting your domain.
Expert view
Expert from Email Geeks clarifies that the domain receiving DMARC reports must explicitly declare its readiness to accept reports about your domain. This mechanism prevents accidental or intentional 'mailbombing,' where an entity could flood a recipient with unwanted DMARC data by simply listing their address. This authorization step is a critical security feature built into the DMARC standard. Without it, the `rua` and `ruf` tags, which specify where reports should be sent, could be abused to launch denial-of-service attacks or to simply harass unsuspecting email administrators with voluminous XML files. Therefore, even if reports are occasionally received without this setup, it is not compliant behavior from the sending Mailbox Provider. Adhering to this requirement is fundamental for the integrity and trustworthiness of the DMARC reporting ecosystem.
Expert view
Expert from Spamresource clarifies that the external authorization DNS record is primarily intended to prevent the abuse of DMARC reporting mechanisms, such as mailbombing attacks. This record acts as a gatekeeper, ensuring that only willing recipients receive potentially large volumes of DMARC data. Without this explicit consent, anyone could specify any email address in their DMARC `rua` tag, potentially overwhelming an unsuspecting recipient with unwanted aggregate reports. This security feature is crucial for maintaining the integrity and usability of DMARC reporting. Mailbox providers, being responsible senders of these reports, are generally expected to perform this check. Failing to do so would make them complicit in potential abuse, undermining the collaborative nature of DMARC for email security.
What the documentation says
Official DMARC documentation and RFCs clearly define the requirement for a specific DNS TXT record when DMARC reports are directed to an external domain. This is not merely a recommendation but a mandatory part of the DMARC specification, primarily serving as an anti-abuse mechanism. The documentation provides precise details on the format and placement of this record, ensuring that only authorized third parties receive potentially sensitive DMARC aggregate data.
Key findings
- RFC 7489 Mandate: Section 7.1 of RFC 7489 explicitly specifies the requirement for a DNS TXT record to authorize the receipt of DMARC aggregate reports at external destinations.
- Anti-Abuse Mechanism: The primary rationale for this record is to prevent 'mailbombing' or unsolicited delivery of reports, thereby enhancing security and privacy.
- Explicit Authorization: The record serves as an explicit consent mechanism from the receiving domain to accept DMARC data from a specific sending domain.
- Suppression of Reports: Without this authorization, DMARC-compliant mail servers are obligated to suppress the generation and delivery of reports to the external destination.
- Internal Exception: The record is not needed if the report-receiving address is within the same organizational domain as the DMARC policy's `From:` domain, as implicit trust is assumed.
Key considerations
- TXT Record Format: The authorization record should be a TXT record located at a specific subdomain, such as <sending-domain>._report._dmarc.<receiving-domain>, with the value v=DMARC1;.
- DMARC.org Guidance: Resources like the DMARC.org FAQ offer practical advice and point back to the RFC for detailed instructions.
- Data Privacy: This explicit authorization mechanism ensures that sensitive DMARC data, which can reveal aspects of email infrastructure, is only delivered to authorized and consenting parties.
- Comprehensive Monitoring: For complete DMARC report coverage and effective monitoring of your domain's email health, adhering to this specific configuration is essential, as some ISPs strictly follow the standard. For more on DMARC reports, consult our resources.
Technical article
Documentation from IETF Datatracker RFC 7489 specifies that Section 7.1, 'External Destinations for Aggregate Reports,' clearly outlines the requirement for a recipient domain to authorize the reception of DMARC reports from an external reporting domain. This authorization is manifested as a specific DNS TXT record. The specification mandates this out-of-band verification to prevent abuse, such as unsolicited email 'mailbombing' with aggregate DMARC reports. It ensures that the receiving entity has explicitly consented to accept these potentially voluminous data streams. This critical security measure helps maintain the integrity of the DMARC reporting ecosystem, fostering trust between sending and receiving domains. Without this record, DMARC-compliant email receivers are obligated to suppress report generation and delivery for that external destination.
Technical article
Documentation from DMARC.org FAQ states that if you publish a DMARC record with reports going to another domain but receive none, 'You need to verify that you are authorized to receive DMARC reports for the domain. See RFC7489, Section 7.1.' This indicates that the problem is not with the DMARC record itself on the sending domain, but with the receiving domain's configuration. The FAQ points directly to the authoritative source, RFC 7489, for the solution, highlighting a common misstep in DMARC setup. The guidance from DMARC.org reinforces the importance of this specific DNS setup for external reporting. It is a frequent point of error for implementers and highlights the need for precise configuration on both the sending and receiving ends of the DMARC reporting chain.
Related resources
8 resources
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