Summary
Managing subdomain reputation with multiple IPs involves a multi-faceted approach combining technical configuration, monitoring, and strategic email practices. Key strategies include proper SPF and DKIM setup, utilizing different DKIM selectors for each sending infrastructure, gradually warming up new IPs, and consistently monitoring IP and domain reputation through tools like Google Postmaster Tools and Microsoft SNDS. DMARC implementation is critical for consistent sender identity. Consider separating email streams by subdomain and IP, delegating subdomains to individual platforms when using multiple sending services, and maintaining consistent sending practices. Setting up feedback loops with mailbox providers and employing A/B testing can further optimize deliverability and engagement. It’s important to remember that IP and domain reputations are distinct and need to be monitored separately, and that when migrating to new platforms a new subdomain is recommended to start with.
Key findings
- SPF/DKIM Alignment: Aligned SPF and DKIM authentication is critical when using multiple IPs for sender addresses.
- Distinct SPF Domains: SPF domains should be different for each setup, allowing for multiple sending infrastructures.
- Gradual IP Warm-up: Ramping up sending volume from new IPs gradually establishes a positive sending reputation.
- Reputation Monitoring: Continuous monitoring of IP and domain reputation identifies deliverability issues early.
- DMARC Enforcement: Proper DMARC implementation ensures consistent sender identity and prevents unauthorized use.
- Stream Separation: Isolating email streams (transactional vs. marketing) helps to mitigate the impact of reputation issues.
- Subdomain Delegation: Delegating subdomains to individual platforms simplifies management and strengthens reputation.
- Consistent Practices: Maintaining consistent sending practices, including volume and content, avoids triggering spam filters.
- Feedback Loops: Setting up feedback loops enables swift detection and resolution of complaint-related reputation problems.
- A/B Testing: A/B testing improves email effectiveness and optimizes deliverability and engagement rates.
- Reputation Distinction: Recognizing that IP and domain reputations are distinct helps in more targeted reputation management.
- AWS Dedicated IP: Utilizing a dedicated IP with Amazon Web Services allows a new IP to build its own reputation.
- Subdomain Strategy: Setting up a new subdomain on the new platform and mapping the from address is recommended for multiple platforms.
Key considerations
- Authentication: Configure SPF and DKIM correctly and ensure alignment across all sending sources.
- Separate Infrastructures: Manage SPF domains to make sure they’re different for each set up.
- Warm-Up Strategy: Plan and implement a phased IP warm-up process.
- Proactive Monitoring: Use reputation monitoring tools frequently to detect and resolve issues proactively.
- Policy Enforcement: Implement a strict DMARC policy to safeguard against domain spoofing.
- Stream Categorization: Categorize and separate email streams to contain reputation damage.
- Platform Integration: Configure each platform with its own subdomain and authentication settings.
- Sending Patterns: Maintain consistent sending volume, frequency, and content relevance.
- Complaint Handling: Address feedback loop complaints promptly to maintain a positive sender image.
- Continuous Improvement: Use A/B testing to adapt and enhance engagement and deliverability continuously.
- Reputation Awareness: Monitor and manage IP and domain reputations individually.
- Infrastructure: When setting up multiple infrastructure, make sure you use different DNS entries.
What email marketers say
8 marketer opinions
Managing subdomain reputation when using multiple IP addresses involves several key strategies. These include warming up new IPs gradually, monitoring IP and domain reputation using dedicated tools, separating email streams (transactional vs. marketing) onto different subdomains and IPs, implementing a robust DMARC policy with proper SPF and DKIM alignment, properly delegating subdomains to each sending platform, maintaining consistent sending practices across all subdomains and IPs, setting up feedback loops to monitor complaint rates, and employing A/B testing to optimize email deliverability and engagement.
Key opinions
- IP Warm-up: Gradually warm up new IPs to establish a positive sending reputation with mailbox providers.
- Reputation Monitoring: Monitor IP and subdomain reputation using tools to identify and address deliverability issues early.
- Stream Separation: Separate email streams (transactional vs. marketing) on different subdomains and IPs to isolate reputation problems.
- DMARC Implementation: Implement a DMARC policy with properly configured SPF and DKIM to authenticate sending sources.
- Subdomain Delegation: Delegate subdomains to each sending platform to ensure separate configurations and reputations.
- Consistent Practices: Maintain consistent sending practices (volume, content, authentication) across all subdomains and IPs.
- Feedback Loops: Set up feedback loops with mailbox providers to monitor complaint rates.
- A/B Testing: A/B test email elements to optimize deliverability and engagement.
Key considerations
- Gradual Warm-up: Introduce new IPs gradually to avoid triggering spam filters and maintain a positive reputation.
- Comprehensive Monitoring: Regularly monitor IP and domain reputation metrics to detect and resolve issues proactively.
- Authentication Alignment: Ensure SPF, DKIM, and DMARC are properly configured and aligned across all sending sources.
- Stream Isolation: Isolate different email streams to prevent reputation issues in one stream from affecting others.
- Platform Configuration: Properly configure each sending platform with its own subdomain and authentication settings.
- Content and Volume Consistency: Maintain consistent content quality and sending volume to avoid triggering spam filters.
- Complaint Monitoring: Actively monitor and address feedback loop complaints to improve sender reputation.
- Ongoing Optimization: Continuously optimize email campaigns through A/B testing to enhance engagement and deliverability.
Marketer view
Email marketer from Validity suggests setting up feedback loops (FBLs) with major mailbox providers for each IP address to monitor complaint rates and identify potential reputation issues quickly.
17 Dec 2022 - Validity
Marketer view
Email marketer from SuperOffice suggests that A/B test different elements of your email campaign, such as subject lines, content, and sending times, to optimize your emails for better deliverability and engagement.
12 Oct 2022 - SuperOffice
What the experts say
5 expert opinions
Managing subdomain reputation when using multiple IP addresses for email sending requires careful attention to authentication, IP warm-up, and infrastructure setup. Experts recommend using aligned SPF and DKIM authentication, ensuring different SPF domains for each setup, and gradually increasing sending volume from new providers. It's also crucial to understand that IP and domain reputation are distinct and should be monitored separately. Proper DMARC implementation is essential for consistent sender identity. When using multiple platforms, setting up a new subdomain on the new platform and mapping the from address on top of it is recommended. Inbound mail can only be received in one place, and hostname DNS entries must be unique for each platform.
Key opinions
- Aligned Authentication: Aligned authentication with SPF and DKIM is crucial for sender addresses when using multiple IPs.
- SPF Domain Differentiation: SPF domains should be different for each setup, but the same d= domain can be used with different DKIM selectors.
- Gradual IP Warm-up: Gradually increase sending volume from new IPs to build reputation.
- Distinct Reputation: IP and domain reputation are related but distinct and should be monitored separately.
- DMARC Importance: Proper DMARC implementation is essential for consistent sender identity.
- New Subdomain Setup: Setting up a new subdomain on the new platform and mapping the from address is recommended for multiple platforms.
- Inbound Mail Restriction: Inbound mail can only be received in one place.
- Unique Hostname DNS: Hostname DNS entries must be unique for each platform.
Key considerations
- Authentication Configuration: Ensure SPF and DKIM are properly configured and aligned for all sending IPs.
- Domain vs. IP Reputation: Monitor both domain and IP reputation separately.
- Volume Ramping: Ramp up sending volume gradually when introducing new IPs or subdomains.
- DMARC Policy: Implement a robust DMARC policy to prevent unauthorized use of your domain.
- Subdomain Strategy: Consider creating new subdomains for different sending platforms.
- Inbound Mail Handling: Define where inbound mail should be received if using multiple platforms.
- DNS Configuration: Ensure DNS records are correctly configured for each sending platform.
- Selector Uniqueness: Use unique DKIM selectors for different sending infrastructures.
Expert view
Expert from Word to the Wise explains that IP address and domain reputation are related, but distinct. You can have a good domain reputation and a bad IP reputation, or vice versa. When using multiple IPs, it's important to monitor the reputation of each one individually.
10 Aug 2021 - Word to the Wise
Expert view
Expert from Email Geeks shares advice based on experience with Salesforce Marketing Cloud, including: 1. Inbound mail can only be received in one place. 2. Hostname DNS entries must be unique for each platform. 3. The best approach is to set up a new subdomain on the new platform and map the from address on top of it.
17 May 2023 - Email Geeks
What the documentation says
5 technical articles
Managing subdomain reputation when using multiple IP addresses involves several technical considerations. SPF records must include all sending IP addresses. DKIM can authenticate email from multiple infrastructures using different selectors. Monitoring tools like Google Postmaster Tools and Microsoft's SNDS program help track reputation. Using dedicated IPs allows building a unique reputation, and proper authentication setup is vital.
Key findings
- SPF Record Updates: SPF records must include all sending IP addresses to validate sending sources.
- DKIM Authentication: DKIM can authenticate email from multiple sending infrastructures using different selectors.
- Reputation Monitoring (Google): Google Postmaster Tools allows monitoring subdomain reputation with Google.
- Reputation Monitoring (Microsoft): Microsoft's SNDS program helps monitor reputation when sending to Outlook.com and Hotmail users.
- Dedicated IPs: Using dedicated IPs allows building a unique sending reputation.
- Authentication Importance: Proper setup of authentication is vital to email deliverability.
Key considerations
- SPF Inclusion: Ensure all sending IP addresses are included in the SPF record to avoid deliverability issues.
- DKIM Selector Management: Use different DKIM selectors for each sending infrastructure for proper authentication.
- Google Monitoring: Regularly monitor Google Postmaster Tools for insights into Google's perception of your sending practices.
- Microsoft Monitoring: If sending to Microsoft domains, utilize SNDS to identify and address reputation issues.
- Dedicated IP Strategy: Evaluate the benefits of using dedicated IPs to control and build your own sending reputation.
- Domain Authentication: Following the AWS documentation and best practices, properly authenticate the domain to ensure delivery to inboxes.
Technical article
Documentation from RFC Editor (RFC 6376) details how DKIM can be used to authenticate email from multiple sending infrastructures. It suggests using different DKIM selectors for each infrastructure to distinguish between them, while still using the same domain.
7 Jan 2025 - RFC Editor
Technical article
Documentation from Microsoft explains that maintaining a good sender reputation is critical to deliverability. Monitoring your reputation via Microsoft's SNDS program (if sending to Outlook.com or Hotmail users) can help you identify if your multiple IPs or subdomains are causing issues.
21 May 2025 - Microsoft
Are custom sending domains worth the money and effort?
Can I use the same subdomain for multiple email sending platforms?
Can I use two subdomains on one dedicated IP address for different email types?
Do I need to set up DMARC for subdomains?
How do I configure reverse DNS (rDNS) with multiple IP addresses for email sending?
Should I use multiple subdomains for different email streams or a single stream?
