Summary
While technically feasible to map multiple subdomains to a single dedicated IP, a wide range of expert and marketer opinions, along with documentation, emphasize the need for careful planning and execution. Factors such as sending volume, email type, and subdomain reputation play crucial roles. Controlling sender reputation, gradual IP warm-up, proper authentication (SPF, DKIM, DMARC), a well defined subdomain strategy tailored to your specific needs and continuous monitoring are highlighted as essential for ensuring deliverability.
Key findings
- Technical Feasibility: Mailing multiple subdomains from a single IP is technically possible.
- Reputation Risk: Mapping multiple subdomains to one IP creates a single point of failure; poor subdomain reputation impacts all.
- Sender Control/Responsibility: Dedicated IPs provide control but mandate responsibility for maintaining a good sending reputation.
- Segmentation benefits: Subdomains and IP segmentation aids isolation of email streams from each other.
- IP Reputation: Existing IP/domain reputation may or may not help a new IP.
Key considerations
- IP Warmup: Gradual IP warm-up is crucial, sometimes needing separate warm-up for each IP/authenticated-domain pair.
- Authentication: Proper authentication (SPF, DKIM, DMARC) is critical.
- HELO/EHLO: Ensure HELO/EHLO domain resolves to the sending IP; avoid changing server HELO.
- Subdomain Strategy: Implement a well-defined subdomain strategy tailored to the customer.
- Sending Volume: Sufficient sending volume may justify separate IPs; otherwise, shared IPs might be more practical.
- Email Type: Separate IPs for transactional vs. marketing emails are beneficial to protect the transactional reputation.
- Reputation monitoring: Continuous monitoring of each subdomain's reputation is crucial.
What email marketers say
10 marketer opinions
Mapping multiple subdomains to a single dedicated IP is technically feasible but presents various deliverability considerations. Several factors influence the optimal approach, including sending volume, email type, and reputation management. Experts recommend careful monitoring and segmentation to mitigate potential risks.
Key opinions
- Feasibility: Mapping multiple subdomains to a single dedicated IP is technically possible.
- Reputation Impact: A subdomain's poor reputation can negatively impact the deliverability of other subdomains sharing the same IP.
- Isolation: Using subdomains allows for isolating the reputation of different email streams.
- Acceptable Use: It's acceptable if subdomains are related and send similar emails, but caution and monitoring are necessary.
- Risk Increase: Using one IP increases the risk of all subdomains being blacklisted.
Key considerations
- Sending Volume: Sufficient sending volume per subdomain justifies separate IPs for better reputation control.
- Email Type: Separate IPs for transactional vs. marketing emails are recommended to protect transactional deliverability.
- Reputation Monitoring: Continuous monitoring of each subdomain's reputation is crucial.
- IP Warmup: Properly warming up IPs with gradually increasing volumes is vital for maintaining deliverability.
- Segmentation: Segmenting IPs based on email type (transactional, marketing) can improve deliverability.
- Subdomain Purpose: The purpose of the subdomains should be taken into consideration, separate IPs may be better for drastically different email streams.
Marketer view
Email marketer from Reddit explains that it's perfectly acceptable to use one dedicated IP for multiple subdomains, especially if they're all related to the same business and sending similar types of emails. However, they caution to monitor deliverability closely.
23 Mar 2022 - Reddit
Marketer view
Email marketer from Email Marketing Forum shares that while technically possible, mapping multiple subdomains to a single IP can create challenges with reputation management. If one subdomain develops a poor reputation, it can affect the deliverability of emails sent from other subdomains using the same IP.
15 Apr 2025 - Email Marketing Forum
What the experts say
6 expert opinions
Experts generally agree that mapping multiple subdomains to a single dedicated IP is technically feasible. However, this approach requires careful consideration of email reputation and potential risks. While it offers flexibility, it's essential to manage the IP's reputation diligently and implement a robust subdomain strategy.
Key opinions
- Technical Feasibility: It is technically possible to mail from multiple subdomains off a single IP address.
- Reputation Risk: Mapping multiple subdomains to a single IP creates a single point of failure for email reputation.
- IP Warming: New IPs require a gradual ramp-up of traffic (warming) to establish a good sending reputation.
- Authenticated Domain: An existing mail stream with a good reputation from the same authenticated domain may or may not help a new IP.
Key considerations
- Server HELO: Avoid modifying the server HELO configuration.
- Subdomain Strategy: Implement a well-defined subdomain strategy tailored to your specific needs.
- IP Warming: Warm up each IP/authenticated-domain pair separately.
- Reputation Management: Implement a good subdomain strategy with strong reputation management
Expert view
Expert from Email Geeks confirms it's okay to use more than one dedicated IP mapped to one sender domain, and then warm up each pair gradually.
10 Sep 2022 - Email Geeks
Expert view
Expert from Email Geeks explains that you can mail multiple 821.From domains off a single IP, and use multiple IPs for a single 821.From. You just shouldn’t start messing with the server HELO.
18 Aug 2022 - Email Geeks
What the documentation says
5 technical articles
Using a dedicated IP provides full control over sender reputation but also places the responsibility of maintaining good standing on the sender. This involves following best practices, gradually warming up the IP, proper authentication (SPF, DKIM, DMARC), maintaining a low spam complaint rate, and ensuring the HELO/EHLO domain resolves to the sending IP.
Key findings
- Sender Control: Dedicated IPs grant full control over the sender's reputation.
- Responsibility: The sender is responsible for maintaining the IP's good standing.
- IP Warmup: Gradual IP warmup is crucial for establishing a positive reputation.
- Authentication: Proper authentication (SPF, DKIM, DMARC) is essential.
- HELO/EHLO: The HELO/EHLO domain must resolve to the sending IP address.
Key considerations
- Best Practices: Adhere to best practices for sending email.
- Spam Traps: Avoid spam traps to protect your reputation.
- Monitoring: Carefully monitor sending metrics.
- Spam Complaints: Maintain a low spam complaint rate.
Technical article
Documentation from Amazon Web Services explains that using a dedicated IP address with Amazon SES allows you to control your sending reputation. AWS recommends carefully monitoring your sending metrics and following best practices to maintain a good reputation.
14 Feb 2023 - Amazon Web Services
Technical article
Documentation from Google Postmaster Tools explains that senders using dedicated IPs should ensure proper authentication (SPF, DKIM, DMARC) and maintain a low spam complaint rate to establish a good reputation with Gmail.
1 Aug 2024 - Google Postmaster Tools
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