How to warm up a new domain when moving email marketing and transactional emails to it?

Key findings

• Phased approach: A deliberate, gradual increase in email volume from the new domain is crucial for building trust with internet service providers (ISPs).
• Domain vs. IP: Domain warm-up is typically less time-consuming than IP warm-up, particularly if utilizing shared IPs with an established good reputation. However, both require careful management.
• Transactional emails: True transactional emails generally do not require a separate warm-up period due to inherently high recipient engagement and expectation.
• Subdomain segregation: Separating marketing and transactional email streams onto distinct subdomains is a widely recommended practice to protect the main domain's reputation.
• Subscriber communication: Proactively informing your audience about the domain change can mitigate negative reactions, although some elevated complaint rates are still to be expected.

Key considerations

• Targeting: Initiate warm-up sends with your most engaged and active subscribers to generate positive reputation signals.
• Volume ramp-up: Start with low daily volumes (e.g., 30,000 emails per day) and gradually increase, potentially doubling the volume weekly to major mailbox providers.
• Compliance: Ensure unsubscribe links remain functional for the required periods by regulations like CAN-SPAM (30 days) and CASL (60 days), even during a transition.
• DNS configuration: Carefully manage DNS records for the new domain and any subdomains to ensure proper authentication (SPF, DKIM, DMARC) and avoid conflicts. For more details, see a simple guide to DMARC, SPF, and DKIM.
• Image hosting: Align image hosting domains with your new sending domain or subdomain to maintain consistent sender reputation signals.
• Monitoring: Actively monitor your new domain's reputation and deliverability performance during the warm-up period. For insights on domain reputation, read a practical guide to understanding your email domain reputation.

Key opinions

• Prioritize engagement: Start warming up the new domain by sending to your most engaged and long-standing subscribers.
• Timeframe flexibility: A 30-day warm-up period for a new domain can be sufficient, especially on shared IPs with good reputations, provided subscriber reactions are positive.
• Permission pass: A pre-switch "permission pass" email can help manage subscriber expectations and reconfirm opt-ins during rebranding.
• Subdomain separation: It is often recommended to use separate subdomains for marketing emails (e.g., e.newsite.com) to protect the root domain from potential deliverability issues associated with marketing sends. Learn more about when switching to a new subdomain.
• Compliance awareness: Mandatory unsubscribe link durations (e.g., 30 days for CAN-SPAM, 60 days for CASL) must be maintained post-send, even with domain changes.

Key considerations

• Subscriber behavior: The success of warm-up depends on positive subscriber engagement. High spam complaints or low engagement from the new domain will hinder reputation building.
• Risk assessment: Evaluate the risk versus reward of a full permission pass, as some subscribers may not re-opt-in, potentially reducing list size.
• Transactional timing: There's an ongoing debate on whether transactional emails should wait for marketing warm-up or move immediately. Many suggest transactional can move sooner due to their nature. Find out more about warming for transactional emails.
• ESP consultation: If changing email service providers (ESPs), consult your new ESP's account manager for a custom warm-up strategy. Read Hand-Delivered Email's guide on warming a new sender domain.
• Image hosting domains: Ensure image hosting domains align with the new sending domain to avoid reputation inconsistencies or DNS overlaps.

Key opinions

• Volume thresholds: For marketing volumes below certain daily thresholds (e.g., 30-50k per mailbox provider), extensive domain warm-up might be less critical, as mailbox providers generally do not share detailed data.
• Transactional vs. marketing: Transactional emails (e.g., receipts, confirmations) typically do not require dedicated warm-up due to high anticipated engagement.
• Dedicated IPs for transactional: Utilizing dedicated IPs for transactional emails is highly beneficial for establishing a strong, reliable reputation for these critical communications.
• Content purity: It is paramount to keep transactional emails strictly transactional; any promotional content can jeopardize the domain's reputation with mailbox providers.
• ISP monitoring: Mailbox providers (like Google and Yahoo) closely monitor user interaction levels, which directly impacts the domain's reputation and deliverability, especially for transactional sends. Understanding Twilio SendGrid's email guide to IP warm up offers valuable insights.

Key considerations

• Subdomain strategy: Unless the new domain is solely for email, it's advisable to host marketing and transactional emails on separate subdomains to maintain distinct reputations. For example, use the root domain for transactional and a subdomain for marketing, or separate subdomains for both.
• Incremental volume: For lists requiring warm-up, a recommended strategy is to start sending around 30,000 emails per day and double the volume weekly until full list capacity is reached, focusing on major mailbox providers like Gmail and Outlook.
• Complaint preparedness: Even with pre-notification, expect some elevated complaint rates during a domain transition. This is a common, albeit undesirable, user reaction to change.
• DNS alignment: Ensure that DNS configurations, including any image hosting domains, align seamlessly with the new sending domains to avoid deliverability issues. This is covered in CleverTap's IP warm-up documentation.

Key findings

• Incremental volume: Domain warming is defined by a slow, controlled increase in the volume of emails sent from the new domain.
• Trust building: This gradual process enables email providers to recognize, learn from, and ultimately trust the new sending domain's behavior.
• Deliverability impact: A well-executed warm-up strategy is a primary driver for achieving and maintaining high email deliverability rates.
• Spam prevention: Proper warming helps prevent the new domain from being perceived as spam or suspicious, thereby avoiding common email blacklists and blocklists.
• Engagement signals: Successful warming depends on generating positive engagement from recipients, which signals to ISPs that the emails are desired.

Key considerations

• Traffic shifting: Gradually transition email traffic from the old domain to the new one, starting with a small percentage and steadily increasing it. This is a best practice for domain warm-up.
• Audience segmentation: Prioritize sending to highly engaged users initially to cultivate a positive sending history.
• List hygiene: Regularly verify email lists to minimize bounces and maintain a healthy sending environment.
• Consistent sending: Maintain a consistent sending volume and pattern throughout the warm-up to build stable trust with ISPs. To assess your domain's health, use an email deliverability tester.
• DNS records: Ensure all necessary DNS records (like SPF, DKIM, and DMARC) are correctly configured for the new domain to enable proper email authentication.