Auto-generated emails are scheduled, pre-written messages sent to customers or users based on specific triggers, such as user actions, system alerts, or scheduled events. Examples include out-of-office (OOO) replies, notifications, and various other automated responses.
Auto-generated messages are alternatively named server-generated emails and there are some specific challenges regarding them from an email security point of view. Because they’re typically sent by automated systems or third-party platforms, ensuring proper email authentication and security can be complex.
Specifically, SPF alignment for these messages is challenging because these messages don’t naturally align with the domain in the “From” address. This misalignment can create issues for DMARC compliance.
Common use cases
Out-of-Office Replies: These emails are often auto-generated by the mail server and sent with a return path from the email system’s domain which is not necessarily the domain in the From header.
System Notifications: Automated alerts about account activity, system status, or billing may be sent by a different server than the main user domain, leading to alignment issues.
Marketing or Transactional Automation: This refers to cases when the third-party platform you’re using sends automated transactional or marketing emails to customers. (e.g., order confirmations, password resets).
It’s important to note that the Return-Path address for server-generated or auto-generated emails is typically empty. When the Return-Path is empty, SPF checks are performed against the HELO/EHLO domain instead which brings the result of the PTR domain and SPF domain matching with each other.
In your aggregate reports, to detect emails that were auto-generated/server-generated, you can pay attention to the PTR source and the return-path domain, for autogenerated emails they appear the same:
However, if we take a closer look, it appears that although these emails failed SPF checks, DMARC is still passing because there is DKIM in place and it ensures the message integrity:
DKIM usage as a solution in regards to auto-generated emails
SPF alignment is a challenge when it comes to auto-generated emails like Out-of-Office replies, system notifications, and other automated messages, as the Mail From domain often differs from the visible From address. The best solution to this challenge is DKIM, which signs the email's headers, including the From address, ensuring the message’s integrity and authenticity. Unlike SPF, which is vulnerable when there is a case related to auto-generated emails, DKIM remains intact regardless of how the email is routed. By signing the email with a cryptographic key, DKIM helps verify that the email hasn't been altered and was indeed sent by the domain owner. Properly configuring DKIM for your domain, subdomains, and any third-party services involved in sending automated emails can significantly improve email deliverability, security, and trust.
Key Benefits of DKIM for Auto-Generated Emails:
- Ensures Authenticity: DKIM signs the email headers, ensuring that the email genuinely originates from the domain owner and hasn't been tampered with.
- Forwarding Resilience: Unlike SPF, DKIM remains effective even if the email is forwarded, as the cryptographic signature stays intact.
- Easy Maintenance: Once DKIM is set up for your domain and subdomains, it automatically signs outgoing emails, reducing manual intervention and improving consistency
In conclusion, even if SPF is properly configured, it can fail under certain conditions, but having DKIM set up and configured ensures better email authentication and security.