Overview

Email warmup is the process of gradually introducing your domain or IP address to ISPs by increasing your sending volume. We offer email warmup as both a process and a managed service to build a positive sender reputation for new domains and dedicated IP addresses. This helps ensure that your emails reach the inbox instead of landing in the spam folder.

Benefits of Email Warmup

• Builds Sender Reputation: ISPs are cautious of new domains and IPs. A gradual warmup tells them your emails are trustworthy and not spam.

• Increases Deliverability: A strong sender reputation helps land emails in inboxes, improving open rates and campaign success.

• Gradual Volume Increase: Begin with a small volume such as 30–100 emails/day) and steadily increase over time to prevent triggering spam filters.

• Essential for New Domains: Warming up is critical for new or inactive domains to avoid blacklisting and deliverability issues.

The warmup process gradually increases email volume, which tells Internet Service Providers (ISPs) that your sending behavior is consistent. Netcore’s warmup plan is automatically configured on your account to help maintain strong deliverability across all future campaigns.

Warm Up a Cold IP

Warming up a cold IP helps build a positive sender reputation with mailbox providers. Without a warmup, sending high volumes from a new or inactive IP can trigger spam filters and block your emails. Follow the given steps to warm up your IP.

Step 1: Set Up DNS and Authentication

• Ensure DNS records like PTR, A, and MX are correctly configured.
• Set up authentication protocols: SPF, DKIM, and DMARC.
• Use a tool like Grademyemail to verify setup.

Step 2: Send to a Productive List

Start by sending emails to your most engaged subscribers. Remember, a productive list is a high-performing list. This includes people who:

• Recently signed up
• Opened or clicked emails in the last 7–15 days
• Recently transacted or visited your website

Avoid using old or purchased lists. Use verified opt-in forms on your website to build and maintain a clean list. Engagement during warmup improves your deliverability.

Step 3: Gradually Increase Volume

Start with a small number of emails (e.g., 100 on Day 1). Increase your daily volume slowly, based on engagement performance.

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Tips

• Avoid sudden spikes in volume or frequency.
• Follow a consistent schedule.
• Monitor open and click rates to adjust accordingly.

Step 4: Segment Smartly

Mailbox providers (MSPs) closely watch your first few campaigns. Use segments with recent activity for the best performance.

Here’s a sample segmentation strategy:

• Segment A: Signed up in the last 5 days + active in past 3 days
• Segment B: Signed up in the last 10 days + active in past 3 days
• Segment C: Signed up in the last 15 days + active in past 5 days
• Segment D: Signed up in the last 30 days + active in past 7 days

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Avoid warming up with inactive subscribers (90+ days of no engagement).

Step 5: Select the Right Mail Stream

Start with emails that naturally drive high engagement.

If you’re a new business, send transactional emails (e.g., confirmations, receipts) from your primary domain. Once the domain gains trust, use a subdomain for marketing campaigns

If you’re an established business, warm up a new IP by gradually migrating engaged users from your old ESP. Slowly split your volume across both IPs while keeping campaigns active

Step 6: Send Relevant and Valuable Content

Ensure your emails match your audience’s interests. Avoid irrelevant or suspicious content. Emails that match customer interests help accelerate warm-up success.

Best practices:

• Provide educational and helpful content
• Use clear calls-to-action
• Start with a welcome series that sets expectations
• Avoid broken or suspicious links—every link is scanned by spam filters

Step 7: Respond to Delivery Feedback

Mailbox providers give real-time feedback on your sending behavior. Providers may throttle or block emails if your volume is too high. Monitor Bounce rates, Delivery errors, and Throttling alerts.

Adjust your delivery rate using adaptive throughput tools if available. These tools help maintain inbox placement and avoid spam folders.

Step 8: Monitor Google Postmaster Tools

Google Postmaster shows:

• Spam complaints
• Domain/IP reputation
• Authentication status
• Feedback loops

Since Gmail users are common, monitoring these metrics helps you track health across the warm-up journey.

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Important Notes

• Use Netcore Email API dashboard to view this data without logging into Google every time.
• If your IP is inactive for 30–60 days, it becomes “cold” again. You must restart the warm-up process.
• Warming up doesn’t guarantee inboxing, but skipping it guarantees trouble.
• Your warm-up plan shapes how MSPs treat your emails.

Email Deliverability Do’s and Don’ts

Refer to the given table to understand Email Deliverability Do’s and Don’ts.