IP Warm-Up for Email Deliverability: Tips and Best Practices

October 05, 2023
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IP Warm-Up for Email Deliverability: Tips and Best Practices

Email is one of the most powerful and effective communication tools. However, the effectiveness of your email campaigns heavily depends on email deliverability—ensuring your emails reach the intended recipients' inboxes. One crucial aspect of optimal email deliverability is the IP warm-up.

IP warm-up is similar to a runner stretching before a marathon—it prepares the email system for optimal performance. Just as a runner cannot start straight into a full sprint without risking injury, sending a large volume of emails suddenly from a new or cold IP address can raise red flags with inbox service providers (ISPs) and email service providers (ESPs). 

These entities are on the lookout for suspicious email activity that often resembles spammer behavior. By gradually increasing the volume of emails sent from a new IP address, your business can establish a reputation as a legitimate email sender to ISPs and improve your email deliverability

Below, we'll dive into what IP warm-up is, why it's essential, and how you can successfully execute it to have the best email deliverability possible.

What is IP warm-up?

IP warm-up refers to gradually establishing a positive sender reputation for a new or underused IP address by incrementally increasing the volume of email sent over that IP address. It's like a trust-building exercise with ISPs to prove your sending practices are legitimate and your emails aren’t spam. 

When an IP address has a solid sender reputation, ISPs are more likely to deliver your emails to the recipients' inboxes rather than sending them to the spam folder.

Why is IP warm-up important?

  • Creates positive deliverability and sender reputations: ISPs carefully monitor sender behavior to protect users from spam and other malicious content. By gradually increasing your sending volume, you demonstrate responsible sending practices and establish a positive sender reputation. This enhances your email deliverability rates.
  • Avoids blocklists: Sending a large volume of emails from a new or inactive IP address can incite red flags with ISPs, potentially leading to your IP address getting blocklisted. IP warm-up helps mitigate this risk by allowing you to build a solid sender reputation over time, reducing the chances of getting blocklisted.
  • Improves engagement metrics: During the warm-up process, you can closely monitor engagement metrics, such as open rates, click-through rates, and spam complaints. Adjusting your strategies based on these metrics can help you fine-tune your campaigns and improve overall engagement. If you start to see a lot of negative signals, such as spam reports or low engagement, slow down your sending and tighten sunsetting practices.
  • Optimizes inbox placement: The ultimate goal of IP warm-up is to establish a trustworthy relationship with ISPs, ensuring your emails consistently land in recipients' primary inboxes. This boosts your chances of getting seen and enhances your brand's credibility.

How to do an IP warm-up (the right way)

  1. Segment your audience: Begin by grouping your subscriber list into smaller daily segments. This allows you to gradually increase your sending volume to each segment, preventing sudden spikes that might incite ISPs concerns.
  2. Start gradually: Send a small volume of emails and increase the volume over several days or weeks slowly. Monitor your engagement metrics closely during this phase. We cover what a manual warm-up could look like in our warm-up guide
  3. Adjust transactional email sending: Consider switching on and off your sending between your old provider and your new one for more time each day until you get to your typical daily sending volume if you send transactional emails. Keep in mind that the nature of transactional emails and the way people engage with them is different from your marketing emails. Sophisticated inbox providers can identify the difference in these emails, especially if you use subdomains to segment the different types of emails.
  4. Automate the warm-up: Use Twilio SendGrid’s automated warm-up feature to help you gradually warm up your new IP, splitting your daily volume between your new IPs and our shared IP Pools. Keep in mind that these pools are for senders sending small to volumes in the millions. If you’re an ultrahigh-volume sender, follow a manual daily schedule or work with our Expert Services to get a custom warm-up plan built around your sending needs.
  5. Monitor ISP performance: Understand how each inbox provider looks at performance, as each uses a different logic to determine reputation and inbox placement. Once you understand your performance and feedback at each provider, use this feedback to adjust your content and targeting strategies.
  6. Focus on engagement: Prioritize sending content that encourages engagement, such as welcome emails, special offers, and valuable information, during warm-up. Positive recipient interactions enhance your sender reputation. 
  7. Maintain consistency: Ensure consistent and relevant content as you increase your sending volume. Erratic sending patterns or sending irrelevant content can negatively impact your sender reputation.
  8. Watch for red flags: Monitor bounce rates, spam complaints, and other negative metrics, such as low unique opens. If issues arise, slow down your sending and focus sending to those you know have engaged recently. 

Tips and best practices for IP warm-up

When executing a successful IP warm-up, the Twilio SendGrid platform offers a range of tools and features to guide you through the process. Here, we'll delve into expert tips for warming up on the SendGrid platform.

1. Familiarize yourself with SendGrid's analytics 

Use the SendGrid Event Webhook or Email Activity Feed to understand your email deliverability performance. Understanding how your emails perform at each inbox provider will be critical in understanding your email deliverability performance over time, but it’s especially crucial to understand performance during warm-up to ensure you have the best warm-up possible. 

2. Segment your transactional mail

Segment your transactional emails by using a subdomain. For example, for our transactional emails, we may use t.sendgrid.com. This lets ESPs know that these emails may look differently than our marketing emails on m.sendgrid.com. Based on user interactions and engagement levels that differ between marketing and transactional emails, you’ll likely want to warm these up differently and segment them between different IPs and subaccounts on the SendGrid platform. 

When warming up transactional emails, consider increasing sending hourly between your current platform and the new setup on SendGrid. Increase how long you keep the sending between each platform until you get to your typical volume daily. Trigger-based messages, like receipts or password resets, can naturally warm up over time, whereas marketing blasts will need warming up gradually. 

3. Focus on relevant and engaging content

Craft emails that encourage recipients to interact with your content during the warm-up phase. Personalized welcome emails and valuable information are excellent choices to use during warm-up. 

The more you personalize sending to how people engage with your brand, the better we see emails perform, and that’s no different during warm-up. High engagement rates contribute positively to your sender reputation, which you establish during this warm-up phase. So keep positive interactions high and negative ones low.

4. Monitor engagement metrics closely

Leverage SendGrid's reporting and analytics tools to monitor critical engagement metrics, such as open rates, click-through rates, and spam complaints. These insights provide a clear picture of how recipients respond to your emails and help you adjust your strategy accordingly.

If you see high spam rates over 0.08% on a campaign or low engagement with unique open rates below 5% at a single inbox provider, try to understand what caused it and slow down, warm up, and focus on sending to those you know will engage with your emails.

5. Maintain transparency and compliance

Ensure your emails are compliant with SendGrid's policies and industry standards, as it’s crucial to your sending reputation that you send wanted and timely emails. 

That includes avoiding misleading subject lines or deceptive content—transparent, legitimate sending practices contribute to a positive sender reputation. Also, implement proper authentication, such as SPF and DKIM.

Warm up your IP with Twilio SendGrid

IP warm-up is a critical step in maintaining strong email deliverability rates and ensuring your messages reach the intended recipients' inboxes. By following these expert tips and utilizing Twilio SendGrid's powerful features, you can effectively warm up your transactional and marketing emails, establish a positive sender reputation, and set yourself up for successful email campaigns that engage your audience and drive results. 

As you navigate the warm-up process on the SendGrid platform, remember that patience, diligence, and a commitment to best practices will lead to improved email deliverability and stronger customer relationships. For a guided warm-up experience and to better understand email deliverability, contact our Expert Services team.  

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