Why IP Warming Matters:
According to ReturnPath, 20% of emails fail to reach recipient inboxes—largely due to poor IP reputation. ISPs like Gmail, Yahoo, Outlook, and AOL evaluate sender reputation based on engagement rates, bounce rates, spam complaints, and sending volume patterns. Without proper warming, emails risk being blocked, throttled, or routed to spam folders. ISPs only store reputation data for 30 days—if you stop sending for a month, you must restart the warming process.
When to Use a Dedicated IP:
Dedicated IP (requires warming): Recommended when sending 100,000+ emails per month. You control your own reputation—other senders' practices don't affect you. For volumes exceeding 2 million emails per day, multiple dedicated IPs are recommended to avoid ISP deferrals.
Shared IP (no warming required): Suitable for lower volume senders who can't establish an independent reputation. However, your deliverability is affected by other senders on the shared IP—one bad actor can harm everyone's reputation.
IP Warming Schedule:
The warming period typically takes 4-6 weeks, with 40-100% volume increases per day. Start with your most engaged subscribers (opened/clicked in the last 30 days), then gradually expand:
Weeks 1-2: Send to subscribers who engaged in the last 30 days. Start with 100-500 emails/day, increasing gradually.
Weeks 3-4: Expand to subscribers who engaged in the last 60 days. Continue scaling volume.
Weeks 5-6: Include subscribers who engaged in the last 90 days. Do NOT send to subscribers with no engagement in 90+ days during warming.
Key rule: A good starting point is 10,000 recipients per day maximum, with consistent daily sending. Avoid weekend sends and holiday periods when engagement typically drops.
Prerequisites Before Warming:
- Configure authentication records: SPF, DKIM, and DMARC verified in DNS
- Register with Google Postmaster Tools and Microsoft SNDS for reputation monitoring
- Set up ISP feedback loops to receive spam complaint notifications
- Clean your list—remove invalid addresses, hard bounces, and inactive subscribers
- Segment your most engaged subscribers for initial sends
Monitoring During Warming:
Track these metrics daily and adjust if warning signs appear:
- Open rates (falling rates indicate engagement issues)
- Bounce rates (pause volume increases if spikes occur)
- Spam complaints (ISPs like AOL want less than 0.2%)
- Deferrals/421 errors (soft bounces retry for 72 hours)
- Unsubscribe rates (high rates signal content relevance issues)
IP Warming in Salesforce Platforms:
Marketing Cloud: Purchase a dedicated IP through the Sender Authentication Package (SAP). Use Automation Studio with SQL queries and Data Extensions for audience segmentation. Monitor via Email Studio deliverability dashboard and Intelligence Reporting.
Account Engagement (Pardot): Uses shared IP pool by default; dedicated IP assigned based on volume and reputation. IP warming may take up to 12 weeks. Use Engagement Studio to monitor engagement rates and adjust frequency.
Key Takeaways
- IP warming takes 4-6 weeks—start with engaged subscribers and gradually increase volume by 40-100% daily
- Dedicated IPs required for 100,000+ emails/month; multiple IPs for 2M+ emails/day
- ISPs store reputation for 30 days—maintain consistent sending to avoid restarting the process
- Native Salesforce email tools can simplify warming with automated verification and engagement tracking
Need to warm your IP address for Salesforce email campaigns? MassMailer provides native Salesforce email marketing with built-in deliverability tools, email verification, real-time analytics, and engagement monitoring to support successful IP warming and long-term sender reputation
