How do you warm up a subdomain for email sending?

Summary

Warming up a subdomain for email sending is a multi-faceted process that requires a strategic approach to building a positive sender reputation. The core principle involves gradually increasing email volume, starting with your most engaged subscribers, and consistently monitoring deliverability metrics such as opens, clicks, bounces, and complaints. Email authentication (SPF, DKIM, DMARC) is paramount, and proper list management, including segmentation and opting-in processes, is crucial for maintaining a clean and engaged audience. The reputation of a subdomain can be independent of the parent domain, requiring careful monitoring. Key factors include content relevance, DNS record configuration, avoiding sudden volume spikes, and actively managing bounces and unsubscribes. The ultimate goal is to establish trust with mailbox providers and ensure that your emails reach the intended recipients' inboxes.

Key findings

  • Gradual Volume Increase: Gradually increase sending volume to build a positive reputation.
  • Engaged Subscribers: Start by sending to your most engaged subscribers.
  • Email Authentication: Implement and maintain SPF, DKIM, and DMARC for authentication.
  • Monitor Deliverability: Continuously monitor deliverability metrics (opens, clicks, bounces, complaints).
  • List Management: Practice good list management, including segmentation and opt-in processes.
  • Subdomain Reputation: Subdomain reputation can be independent of the parent domain, requiring careful monitoring.

Key considerations

  • Content Relevance: Ensure content is relevant and personalized to avoid spam complaints.
  • DNS Configuration: Correctly configure and monitor DNS records.
  • Avoid Sudden Spikes: Avoid sudden spikes in email volume, which can harm reputation.
  • Bounce Management: Actively manage bounces and unsubscribes to maintain a clean list.
  • Complaint Rates: Keep complaint rates low to protect your sender reputation.
  • Text to image ratio: Ensure email content has a good text to image ratio to avoid being flagged as spam.

What email marketers say
12Marketer opinions

Warming up a subdomain for email sending involves a gradual process focused on building a positive reputation with mailbox providers. Experts recommend starting with low sending volumes to your most engaged subscribers and gradually increasing the volume over time. Monitoring sender reputation and engagement metrics (opens, clicks, bounce rates, complaints) is crucial. Proper email authentication (SPF, DKIM, DMARC) is essential, and segmenting email lists based on engagement levels helps to ensure that the most active subscribers receive emails first. Some experts suggest that subdomain reputation is treated independently, so careful monitoring is important. Overall, a consistent sending schedule, relevant content, and proactive list management are key to a successful subdomain warm-up.

Key opinions

  • Gradual Ramp-Up: Start with low sending volumes and gradually increase over time.
  • Engaged Subscribers: Focus on sending to your most engaged subscribers initially.
  • Monitor Metrics: Monitor sender reputation, engagement metrics (opens, clicks), and bounce rates.
  • Authentication: Ensure proper email authentication (SPF, DKIM, DMARC) is configured.
  • Segmentation: Segment your email lists based on engagement levels.
  • Independent Reputation: Subdomain reputation may be treated independently from the parent domain.

Key considerations

  • Sending Volume: Avoid sudden spikes in email volume; increase gradually.
  • Content Relevance: Focus on relevant and personalized content to avoid spam complaints.
  • List Hygiene: Maintain a clean email list by managing bounces and unsubscribes.
  • Feedback Loops: Pay attention to feedback loops and react quickly to negative signals.
  • DNS Records: Ensure all DNS records are configured correctly and monitored.
  • Text to image ratio: Ensure a good text to image ratio to avoid being flagged as spam.
Marketer view

Marketer from Email Geeks suggests gradually changing out the domain while still using all the IPs, focusing on warming the domain rather than the IPs. No need to gradually use the IPs, just gradually use the domain.

October 2023 - Email Geeks
Marketer view

Marketer from Email Geeks shares their experience that root domain rep does not seem to carry to subdomain variations, as Google gives a different rep treatment for each sub even if they're on the same root.

November 2023 - Email Geeks
Marketer view

Email marketer from SendGrid.com advises a gradual ramp-up, suggesting starting with your most engaged users. Monitor deliverability using tools like Google Postmaster Tools. Focus on content relevance and personalization to avoid spam complaints. Maintain consistent sending habits.

December 2023 - SendGrid.com
Marketer view

Email marketer from Mailgun.com recommends starting with low volumes and gradually increasing the sending volume over time. It's crucial to monitor your sender reputation and engagement metrics (opens, clicks) to ensure positive signals are being sent to mailbox providers. This involves sending to engaged users first and segmenting your lists.

September 2021 - Mailgun.com
Marketer view

Email marketer from Reddit shares that focusing on sending to engaged subscribers (those who have recently opened or clicked) is key when warming a subdomain. Monitor bounce rates and adjust sending volume accordingly. Avoid sending to old or unengaged lists during the warm-up phase.

October 2021 - Reddit
Marketer view

Email marketer from GlockApps.com shares some general advice is to ensure all of your DNS records are setup correctly and that you are monitoring them. Also ensure your email content has a good text to image ration to avoid being flagged as spam.

May 2024 - GlockApps.com
Marketer view

Email marketer from SparkPost.com recommends starting with a small subset of your most engaged subscribers and gradually increasing volume. Pay close attention to bounce rates and feedback loops to react quickly to any negative signals. They emphasize the importance of authentication (SPF, DKIM, DMARC).

December 2021 - SparkPost.com
Marketer view

Marketer from Email Geeks mentions that it depends on the methods the receiver uses. Some treat SLDs differently than ThLDs or treat them independently. Having independent reputation doesn't mean the IP reputation isn't also important when evaluating the domain reputation, etc.

November 2022 - Email Geeks
Marketer view

Marketer from Email Geeks advises picking a mail stream, keeping the existing DKIM signing config and doing a test on x% of traffic to determine the next course, emphasizing the importance of individual mail stream quality and recipient mailbox provider breakdown.

October 2024 - Email Geeks
Marketer view

Marketer from Email Geeks says that while Google may provide a unique reputation score for each sub-domain, the reputation of the parent and sibling domains is still a factor in deliverability. He suggests introducing the subdomain as an additional DKIM signature to start building its reputation without being too disruptive.

December 2023 - Email Geeks
Marketer view

Email marketer from Gmass.co explains to ensure that you're set up with SPF, DKIM, and DMARC and that you are gradually increasing your volume to warm up the IP address. Do not start with mass sends that are not targeted as they will likely end up straight in the junk folder.

July 2021 - Gmass.co
Marketer view

Email marketer from Email Marketing Forum suggests segmenting your email list based on engagement levels. Start with sending to the most active subscribers and gradually include less engaged users as your reputation improves. Check your IP/domain reputation regularly using reputation monitoring services.

June 2024 - Email Marketing Forum

What the experts say
2Expert opinions

Warming up a subdomain requires careful attention to reputation, deliverability metrics, and list management. Experts emphasize the importance of sending to engaged subscribers and maintaining a clean email list. Monitoring deliverability metrics and segmenting sending based on engagement is crucial to ensure a smooth warm-up and protect overall domain reputation. Ensuring proper authentication such as SPF and DKIM is critical.

Key opinions

  • Separate Reputation: Subdomain reputation is often treated separately from the main domain.
  • Clean, Engaged List: Sending to a clean, engaged list is crucial during subdomain warm-up.
  • Double Opt-In: Using a double opt-in process helps ensure subscribers are genuinely interested.
  • Authentication is Key: Authentication with SPF and DKIM must be configured properly.

Key considerations

  • Monitoring Deliverability: Carefully monitor deliverability metrics.
  • Segmentation: Segment sending based on engagement.
  • List Hygiene: Actively manage bounces and unsubscribes to maintain list hygiene.
  • Avoid Spam Traps: Take steps to avoid spam traps.
Expert view

Expert from Spam Resource emphasizes that sending to a clean, engaged list is crucial during subdomain warm-up. He suggests using a double opt-in process to ensure subscribers are genuinely interested and actively managing bounces and unsubscribes to maintain list hygiene. This helps avoid spam traps and protects sender reputation.

June 2021 - Spam Resource
Expert view

Expert from Word to the Wise explains that subdomain reputation can be separate from the main domain. She recommends carefully monitoring deliverability metrics and segmenting sending based on engagement to ensure a smooth warm-up and protect overall domain reputation. Ensuring proper authentication like SPF and DKIM is crucial.

May 2024 - Word to the Wise

What the documentation says
3Technical articles

Warming up a subdomain for email sending, as detailed in various documentation sources, involves several key practices centered on establishing a positive sender reputation. Crucially, consistent email authentication (SPF, DKIM, DMARC) is paramount. Gradually increasing sending volumes, avoiding sudden spikes, and maintaining low complaint rates are essential. Best practices for list management, sending wanted mail, and monitoring reputation over time using available tools are also important.

Key findings

  • Email Authentication: Consistent authentication (SPF, DKIM, DMARC) is critical for establishing sender reputation.
  • Gradual Volume Increase: Warming up involves gradually increasing sending volumes to build trust.
  • Avoid Sudden Spikes: Sudden spikes in email volume can negatively impact sender reputation.

Key considerations

  • List Management: Adhere to best practices for list management to maintain a positive reputation.
  • Complaint Rates: Maintaining low complaint rates is crucial for avoiding deliverability issues.
  • SPF Record Setup: Properly formatted SPF records are essential for authentication.
  • Wanted Mail: Ensure you are sending mail that recipients want to receive.
  • Reputation Monitoring: Monitor your reputation over time using available tools.
Technical article

Documentation from Microsoft.com details that warming up a domain/subdomain involves gradually increasing sending volumes. Maintaining low complaint rates and adhering to best practices for email authentication and list management are crucial for building and maintaining a positive reputation.

June 2024 - Microsoft.com
Technical article

Documentation from RFC-Editor.org explains the setup of SPF records and importance of having a correctly formatted SPF record to assist with authentication. It is important to have your SPF setup correctly to ensure reputation.

March 2021 - RFC-Editor.org
Technical article

Documentation from Google Postmaster Tools Help explains that establishing a good sender reputation involves consistently authenticating your emails (SPF, DKIM, DMARC), sending wanted mail, and avoiding sudden spikes in email volume. They provide tools to monitor your reputation over time.

December 2024 - Google Postmaster Tools Help