Summary
Identifying email sending vendors for DMARC enforcement involves a comprehensive approach combining technical analysis, internal communication, and policy enforcement. Analyzing DMARC reports, SPF records, and authentication results provides valuable insights into sending sources. Engaging internal departments like Finance, Sales, and Marketing helps uncover vendor usage. Maintaining a detailed inventory of authorized senders and regularly auditing them is crucial. Starting DMARC in monitoring mode allows for proper vendor identification before enforcement. New vendor contracts should require a list of IPs and domains used for sending. Employing automated vendor discovery tools and ensuring visibility into email channels streamline the process. Addressing policy issues related to multiple accounts and having a process for vendor approval are essential for effective DMARC management.
Key findings
- DMARC Reporting: DMARC aggregate reports provide critical data on sending sources, including IPs, domains, and authentication results.
- SPF Records: SPF records identify authorized mail servers, aiding in the identification of legitimate vendors.
- Internal Communication: Engaging Finance, Sales, and Marketing teams helps uncover vendor usage.
- Vendor Inventory: Maintaining an up-to-date inventory of all authorized sending sources (ESPs, vendors) is essential.
- Vendor Contracts: Requiring a list of sending IPs/domains in vendor contracts aids in identification.
- Authentication Tools: Email platforms offer tools to review authentication results and pinpoint sending sources.
- Email Channels: Visibility into all email channels helps discover all sending vendors.
Key considerations
- Phased Rollout: Start DMARC in monitoring ('p=none') mode to gather data before enforcement.
- Vendor Approval Process: Establish a process for getting vendors and domains approved before they come online.
- Regular Audits: Regularly audit authorized senders to compare with known vendors.
- Third Party DKIM: Consider the potential to delegate third-party DKIM signers.
- Authentication Alignment: Ensure all legitimate sending sources are properly authenticated (SPF, DKIM).
- IP Netblocks: Using IP Netblocks is a good method.
What email marketers say
17 marketer opinions
Identifying email sending vendors for DMARC enforcement involves several key strategies. Analyzing DMARC reports is crucial for understanding who is sending mail on your behalf. This includes reviewing IPs, domains, and authentication results. Maintaining a detailed inventory of authorized sending sources and regularly auditing them is also essential. Communication with internal departments, particularly finance and marketing, helps uncover vendors they use. Contracts with new vendors should include a requirement to list IPs/domains used for sending email. Starting DMARC in monitoring mode before enforcement allows for proper vendor identification. Utilizing SPF records to list authorized senders is another key element. Additional tips include using automated vendor discovery tools, checking DNS logs, and sending sample emails to identify vendor infrastructure.
Key opinions
- DMARC Reporting: DMARC aggregate reports provide critical data on sending sources, including IPs and domains.
- Vendor Inventory: Maintaining an up-to-date inventory of all authorized sending sources (ESPs, vendors) is essential.
- Internal Communication: Checking with internal departments and appointing supplier managers is helpful for vendor discovery.
- Vendor Contracts: Requiring a list of sending IPs/domains in vendor contracts aids in identification.
- Auditing Vendors: Regularly auditing your authorized senders by comparing your known vendor list with the IPs and domains sending mail under your name is essential for DMARC.
- SPF records: Listing senders in the SPF records means they will not fail the DMARC process.
Key considerations
- Phased Rollout: Start DMARC in monitoring ('p=none') mode to gather data before enforcement.
- Authentication Alignment: Ensure all legitimate sending sources are properly authenticated (SPF, DKIM).
- Reporting Delays: Be aware that it can take time to start receiving and analyze DMARC reports.
- Tool Selection: Consider using automated vendor discovery tools to simplify the process.
- Third Party DKIM: Delegate third-party DKIM signers.
Marketer view
Email marketer from Email Geeks suggests checking the logs from the change committee that owns the DNS for SPF-related information to identify vendor relationships.
27 Feb 2025 - Email Geeks
Marketer view
Email marketer from Email Geeks states that the DMARC aggregate report lists sending IP (sample) followed by the 5322.From, the 5321.From (SPF domain), the DKIM signing domain(s) and selector(s) along with the policy decision.
7 Mar 2024 - Email Geeks
What the experts say
8 expert opinions
Identifying email sending vendors for DMARC enforcement requires a multi-faceted approach. Experts recommend leveraging internal resources like Finance, Sales, and Marketing to uncover vendor usage. Examining IP addresses, vendor lists, and SPF records provides valuable insights. Starting with a relaxed policy (p=none) and gradually increasing enforcement is advised. It's crucial to have a process for vendor approval and to address policy issues related to multiple accounts.
Key opinions
- Leverage Internal Resources: Consult Finance, Sales, and Marketing teams to identify vendors they utilize.
- Examine IP Addresses: Check the IPs that mail is sending from to identify vendor ownership.
- SPF Records: Perform SPF lookups to determine approved email service providers.
- Vendor Contracts: Include a requirement for vendors to provide a list of sending IPs and domains.
- Vendor Lists: Start with an approved vendor list and verify backend systems.
Key considerations
- Phased Enforcement: Begin with 'p=none', then quarantine, and finally reject to avoid disrupting legitimate mail flow.
- Vendor Approval Process: Establish a process for getting vendors and domains approved before they come online.
- Policy Issues: Address policy issues related to multiple accounts, such as Mailchimp, to maintain messaging control and compliance.
- Out of Scope: Designate certain accounts as 'out of scope' and block them from sending if necessary.
- Back End System: Ask about the vendors back end systems.
Expert view
Expert from Word to the Wise shares the advice to never dive straight into enforcement. Starting too aggressively with DMARC before fully understanding your email ecosystem and identifying all legitimate sending sources can lead to deliverability issues. Begin in monitoring mode to gather data and identify vendors before enforcing policies.
23 Jun 2021 - Word to the Wise
Expert view
Expert from Email Geeks notes that multiple Mailchimp accounts bring up a number of other policy issues that should be addressed when it comes to controlling messaging, anti-spam compliance etc.
27 Apr 2023 - Email Geeks
What the documentation says
5 technical articles
Identifying email sending vendors for DMARC enforcement involves analyzing email authentication data. SPF records specify authorized mail servers, while DMARC aggregate reports offer insights into sending sources and their compliance. Microsoft 365 tools help pinpoint sending sources by reviewing authentication results. Automated vendor discovery tools simplify identifying all services sending email on your behalf. Visibility into email channels and monitoring outbound traffic reveals authorized and unauthorized email sources, supporting better DMARC enforcement.
Key findings
- SPF Records: SPF records identify authorized mail servers, aiding in the identification of legitimate vendors.
- DMARC Reports: DMARC aggregate reports provide insights into email sending sources and their authentication compliance.
- Authentication Tools: Microsoft 365 tools can help pinpoint sending sources through email authentication result analysis.
- Automated Discovery: Automated vendor discovery tools streamline the process of identifying all services sending email on your behalf.
- Visibility: Gaining visibility into email channels through monitoring outbound traffic helps uncover both authorized and unauthorized email sources.
Key considerations
- Implementation Order: SPF implementation is a critical first step before DMARC enforcement.
- Report Analysis: Regularly analyze DMARC reports to identify potential unauthorized email activity.
- Tool Utilization: Effectively use the email authentication reports and tools available within platforms like Microsoft 365.
- Proactive Monitoring: Proactively monitor and address potential unauthorized email activity and update DMARC policies accordingly.
- Vendor Assessment: Assess vendors complience with authentication protocols.
Technical article
Documentation from Valimail mentions that using automated vendor discovery tools simplifies identifying all services sending email on behalf of your domain. These tools analyze DMARC reports and network data to provide a comprehensive list of vendors, streamlining DMARC compliance efforts.
24 Jan 2022 - Valimail
Technical article
Documentation from DMARC.org explains that analyzing DMARC aggregate reports is key. These reports provide insights into the sources sending email using your domain, allowing you to identify vendors and assess their compliance with authentication protocols.
27 Feb 2023 - DMARC.org
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