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How to warm up a new domain

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  1. We followed a best practice we always recommend: separating transactional, marketing, and product-generated emails onto different domains. Subdomains help protect deliverability by ensuring that issues with one type of email (e.g., marketing campaigns) don’t negatively impact critical transactional emails. In one way, however, this added a bit of complexity to our warm-up plan. We needed to warm up three domains instead of just one. Also, brand-new domains—those registered only recently—often face even more scrutiny because spammers frequently buy fresh domains and burn them out quickly.

    In Domain and mailbox architecture

  2. 3. Which subdomains to use? We followed a best practice we always recommend: separating transactional, marketing, and product-generated emails onto different domains. Subdomains help protect deliverability by ensuring that issues with one type of email (e.g., marketing campaigns) don’t negatively impact critical transactional emails.

    In Domain and mailbox architecture

  3. What key questions should you ask? The easiest way to approach domain warm-up is to work backwards from your target goals by asking key questions. What volume will you be sending?

    In Mailbox warm-up

  4. When a domain with no sending history suddenly starts blasting out emails, inbox providers take notice. Since they prioritize protecting their users from spam, they’ll often take a cautious approach, closely monitoring engagement signals like opens, clicks, and spam complaints. If they don’t see positive engagement—or worse, if users start marking your emails as spam—your domain’s reputation takes a hit, making it harder or impossible for your emails to reach the inbox.

    In Mailbox warm-up

  5. Since they prioritize protecting their users from spam, they’ll often take a cautious approach, closely monitoring engagement signals like opens, clicks, and spam complaints. If they don’t see positive engagement—or worse, if users start marking your emails as spam—your domain’s reputation takes a hit, making it harder or impossible for your emails to reach the inbox. Think of it like building credit. At first, lenders don’t know if they can trust you, so you have to start small and establish reliability over time. Without this reputation, inbox providers might slow down your deliveries, send your emails straight to spam, or even block them entirely.

    In Mailbox warm-up

  6. If they don’t see positive engagement—or worse, if users start marking your emails as spam—your domain’s reputation takes a hit, making it harder or impossible for your emails to reach the inbox. Without this reputation, inbox providers might slow down your deliveries, send your emails straight to spam, or even block them entirely. Since this is a topic that often concerns our customers, we wanted to transparently share our own experience warming up a domain that was critical to our business.

    In Mailbox warm-up

  7. This wasn’t just for organization—it was a deliberate strategy to protect our reputation. If marketing emails ever ran into deliverability issues, our critical transactional messages wouldn’t be affected. Inbox providers evaluate sending reputation at the domain and subdomain level. 3. Gradually increase sending volume

    In Sender reputation

  8. Why do we have to warm up a domain? When a domain with no sending history suddenly starts blasting out emails, inbox providers take notice. Since they prioritize protecting their users from spam, they’ll often take a cautious approach, closely monitoring engagement signals like opens, clicks, and spam complaints.

    In Sender reputation

  9. When a domain with no sending history suddenly starts blasting out emails, inbox providers take notice. Since they prioritize protecting their users from spam, they’ll often take a cautious approach, closely monitoring engagement signals like opens, clicks, and spam complaints. If they don’t see positive engagement—or worse, if users start marking your emails as spam—your domain’s reputation takes a hit, making it harder or impossible for your emails to reach the inbox.

    In Sender reputation

  10. Make sure you’re sending to high-quality, engaged recipients. Increase your sending volume gradually over time. Monitor your deliverability metrics and adjust as needed.

    In Sending rate and volume controls