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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.

Why warm-up matters

Without warm-upWith warm-up
Inbox providers flag high-volume sends from unknown domainsGradual volume lets providers build a reputation profile
High bounce and spam rates trigger immediate blocksEngagement metrics establish trust
Recovery from a bad reputation takes monthsPositive reputation compounds over time

The warm-up schedule

DayDaily volumeNotes
1-325-50Send to your most engaged contacts only
4-750-100Continue targeting high-engagement contacts
8-14100-250Expand to moderately engaged contacts
15-21250-500Begin including broader segments
22-28500-1,000Monitor bounce and complaint rates closely
29-351,000-2,500If metrics are healthy, continue scaling
36-422,500-5,000Approaching normal volume
43+5,000+Full volume with best practices
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.

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

Monitoring metrics during warm-up

MetricTargetAction if below target
Open rate25%+Improve subject lines or send to more engaged contacts
Click rate3%+Improve content and CTAs
Bounce rateBelow 2%Clean your list and verify addresses
Spam complaint rateBelow 0.05%Ensure contacts are opted in
Use Google Postmaster Tools and Microsoft SNDS to monitor reputation during warm-up.

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.

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