What are the best practices for email domain authentication across corporate and marketing mail?

Key findings

• Universal authentication: All email sending domains, whether for corporate communication or bulk marketing, should be authenticated with SPF, DKIM, and DMARC.
• Subdomain strategy: Using separate subdomains for marketing emails is a recommended practice to segregate and protect the sending reputation of different email streams.
• DMARC for brand protection: DMARC provides robust protection against email spoofing and phishing, safeguarding your brand's identity across all email operations. Implementing a DMARC policy, even a p=none policy initially, is beneficial.
• Reputation isolation: Separating marketing and corporate mail through subdomains helps prevent deliverability issues from one affecting the other.

Key considerations

• DMARC implementation: Careful planning is needed when moving to stricter DMARC policies (like p=quarantine or p=reject) to avoid legitimate corporate emails failing authentication if they are not properly set up. You can learn more about this in our article on safely implementing DMARC p=reject.
• SPF record complexity: Managing SPF records for domains with numerous outgoing IP addresses or various sending sources requires careful configuration, including the use of subnets, ranges, and macros, to avoid exceeding DNS lookup limits.
• No mail domains: Even domains that do not send emails should have authentication records in place to prevent them from being spoofed by malicious actors.
• Evolving requirements: Mailbox providers like Gmail and Yahoo are continually updating their authentication requirements, making ongoing compliance crucial for deliverability. Staying informed about these changes is essential. An article by Mailgun highlights current requirements.

Key opinions

• Subdomain for ESPs: Many marketers strongly advocate for using a subdomain when sending marketing emails through an ESP to separate authentication and manage domain reputation more easily. This allows for clear distinctions in MailFrom and Friendly From addresses.
• Bounce handling: Questions arise about how bounces are handled, specifically whether the Return-path address aligns with the client's domain or the ESP's sending domain.
• Corporate mail impact: There is a concern that unauthenticated corporate mail could negatively affect the deliverability of marketing mail, especially if both use the same root domain.
• Proactive authentication: Even without current deliverability issues, marketers believe it's prudent to authenticate all domains to future-proof against potential problems and comply with evolving ISP requirements.

Key considerations

• Root domain DMARC: Marketers must consider the implications of setting up a DMARC policy on their root domain, particularly if corporate emails are not fully authenticated, as this could lead to unintended failures. You can learn more about domain alignment best practices.
• SPF record management: For organizations with many outgoing IP addresses, correctly configuring SPF records can be complex, requiring knowledge of subnets and other advanced SPF mechanisms to avoid DNS lookup limits. An article from FluentCRM provides a complete guide.
• Visibility into ESP setup: Understanding whether the ESP's SPF domain or the client's domain is used for authentication is crucial for proper configuration and troubleshooting.
• Risk assessment: Marketers often weigh the risks of not authenticating against the effort of implementation, especially if no immediate deliverability issues are apparent.

Key opinions

• Mandatory authentication: Experts firmly believe that SPF, DKIM, and DMARC should be set up for all domains sending email, including corporate and marketing subdomains.
• Brand identity protection: DMARC is highlighted as a powerful tool for safeguarding a brand's identity and preventing malicious spoofing, making the effort of implementation worthwhile.
• Subdomain benefits: Using subdomains for marketing mail sent via an ESP simplifies authentication management and helps to isolate IP and domain reputation.
• SPF for large IP sets: SPF is capable of handling a large number of outgoing IP addresses through the use of subnets, IP ranges, and advanced macros, making it adaptable for diverse corporate sending environments.

Key considerations

• DMARC policy impact: If the visible 'From' address uses the root domain for both corporate and marketing mail, implementing a DMARC policy on that root domain could cause corporate emails to fail if they lack proper SPF or DKIM authentication.
• DNS complexity: Configuring SPF, DKIM, and DMARC records correctly within DNS settings is crucial, and errors can lead to authentication failures. Understanding where to place these records is a common challenge.
• Unused domains: Even domains that are not actively used for sending email should have DMARC records in place (e.g., with a p=reject policy) to prevent malicious actors from spoofing them.
• Strategic implementation: It's not just about implementing, but implementing correctly. For example, Word to the Wise emphasizes the critical link between DMARC policy and overall deliverability.

Key findings

• Core protocols: SPF, DKIM, and DMARC are recognized as the primary methods for authenticating email senders and establishing trust with recipient mail servers.
• Verification and anti-spoofing: These protocols work in concert to verify that an email originates from an authorized sender and has not been tampered with, thereby combating phishing and spoofing. Mailchimp's documentation provides further detail on email authentication protocols.
• Improved deliverability: Proper implementation of these standards significantly increases the likelihood of emails reaching the inbox, improving overall deliverability rates.
• ISP requirements: Major ISPs like Google, Yahoo, and Microsoft have tightened their requirements, making domain authentication a prerequisite for high-volume senders.

Key considerations

• DNS records: Implementing SPF, DKIM, and DMARC requires publishing specific DNS records (TXT records) for your domain. Accurate configuration is essential. You can find DMARC record and policy examples on our site.
• Domain alignment: For DMARC to pass, the domain in the From header must align with the domain authenticated by SPF or DKIM. This alignment is critical for overall policy enforcement.
• Policy progression: DMARC policies typically start with p=none for monitoring before progressing to stricter policies like p=quarantine or p=reject as confidence in authentication grows.
• Troubleshooting: Documentation often provides guidance on common issues, such as "DMARC verification failed" errors or SPF TempError messages, which require careful review of DMARC reports.