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When you start sending email from a new domain or IP address, inbox providers have no history to judge your reputation. Sending large volume immediately signals spam behavior. Warming up means gradually increasing volume over several weeks so providers can build a positive reputation for your domain.

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Why warm-up matters

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The warm-up schedule

Do not skip warm-up stages. If your bounce rate exceeds 3% or spam complaint rate exceeds 0.05% at any stage, pause and clean your list before continuing.

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Content tips during warm-up

  • Write clear, recognizable subject lines with your brand name
  • Use plain-text or simple HTML templates
  • Include a clear unsubscribe link in every message
  • Avoid spam-trigger words: “free”, “act now”, “limited time”
  • Personalize content with the recipient’s name
  • Keep your email-to-text ratio balanced

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Monitoring metrics during warm-up

Use Google Postmaster Tools and Microsoft SNDS to monitor reputation during warm-up.

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HoopAI’s warm-up model

The HoopAI platform uses a fixed-stage warm-up for dedicated sending domains:
  1. When you set up a new dedicated sending domain, the platform automatically limits daily sending volume
  2. Limits increase in stages as the platform monitors your deliverability metrics
  3. Track warm-up progress in Settings > Email Services > Dedicated Domain
  4. The platform notifies you if metrics fall below acceptable thresholds
Automatic warm-up limits apply to the dedicated sending domain only. For third-party SMTP providers (Mailgun, SendGrid), manage the warm-up manually.

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Troubleshooting slow warm-up

Common in the first 1-2 weeks. Ensure SPF, DKIM, and DMARC are correctly configured. Send to engaged contacts only.
Check that your From name is recognizable. Some inbox providers initially place emails in the Promotions tab.
Check your bounce and complaint rates. High rates cause the warm-up to pause or reset. Clean your list before continuing.
Last modified on March 6, 2026