Why is IP warming so important for new IP addresses?

IP warming is crucial because new IP addresses have no sending history, so ISPs don't trust them immediately. Without a gradual increase in sending volume, ISPs are likely to flag large sends from a new IP as suspicious, leading to emails being rejected or sent to spam folders. This process builds a positive sender reputation with ISPs.

What happens if a warmed IP address goes inactive for an extended period?

If an IP address that has been warmed goes idle for a month or two, it essentially becomes cold again. ISPs expect consistent sending patterns. A prolonged period of inactivity followed by a sudden increase in volume will negatively impact your sender reputation, necessitating a re-warming process.

What kind of emails should I send first when warming up a new IP?

Starting with highly engaged audiences, such as those in your welcome flow journey, is ideal for IP warming. These subscribers are more likely to open and click your emails, providing positive engagement signals to ISPs. This helps build a good sender reputation faster and more reliably.

Does my domain reputation affect deliverability on a new IP?

Yes, your domain reputation plays a significant role in deliverability, alongside your IP reputation. ISPs consider both when evaluating your emails. A clean domain history, proper authentication (SPF, DKIM, DMARC), and consistent sending practices across all your subdomains contribute to overall positive sender reputation.

What are the benefits of consolidating multiple email sending platforms?

Consolidating platforms streamlines operations, reduces complexity, and potentially lowers costs. It also gives you a centralized view of your email performance, allowing for more consistent application of deliverability best practices and better overall control over your sender reputation.

How to consolidate email sending platforms and warm up a new IP for improved deliverability? - Technical - Email deliverability - Knowledge base

Moving an organization from multiple email sending platforms to a single, unified solution can feel like a monumental task. The appeal of streamlined operations and cost savings is clear, but the underlying complexity of email deliverability can be daunting. My biggest concern when tackling such a project is always understanding the current email quality across all existing tools. The hope is that a new IP address within a new Email Service Provider (ESP) offers a clean slate, a chance to start fresh with a solid sender reputation.

However, it's not simply a matter of plugging in the new IP and sending away. The process requires careful planning, especially when it comes to IP warming. If an IP has been quiet for a month or two after an initial warm-up, it essentially becomes cold again, necessitating a re-warm. The good news is that with a strategic approach, even without a dedicated budget for re-warming, you can effectively consolidate your sending and build a robust sender reputation.

Understanding sender reputation and IP warming

When you embark on consolidating email sending platforms, the goal is to enhance overall email deliverability. This means ensuring your messages land in the inbox, not the spam folder. A key factor in this is sender reputation, which internet service providers (ISPs) like

Google and

Yahoo heavily rely on. Your sender reputation isn't solely tied to your IP address, but also significantly to your sending domain. Even with a new IP, your domain carries a lot of its historical reputation, both good and bad.

The consolidation process offers an opportunity to clean up your sending practices. By moving to a single platform, you gain a clearer overview of your email quality and can apply consistent best practices. This includes identifying and eliminating poorly performing emails and migrating only your most engaged audiences. This focused approach helps build a stronger, more positive sender reputation from the outset on your new infrastructure.

While a new IP offers a fresh start, it lacks a sending history, meaning ISPs don't yet trust it. They will initially throttle (limit) the volume of emails it can send. This is why IP warming is essential. Without proper warming, a sudden high volume of mail from a new IP is likely to trigger spam filters and result in emails being blocked or landing in the spam folder. Understanding why IP warming matters for email marketing is crucial for maintaining good deliverability rates.

The importance of the IP warming process

The core of IP warming involves gradually increasing the volume of email sent from a new IP address over a period of time. This slow and steady approach allows ISPs to observe your sending behavior, build trust, and recognize your IP as legitimate. Starting with a low volume of highly engaged subscribers and then progressively expanding your reach signals to ISPs that you are a responsible sender. You can find email example schedules for IP warming to guide this process.

A common mistake, as I've encountered, is having an IP warmed up, only for it to sit idle for weeks or months. If an IP remains quiet for an extended period, it loses the reputation it initially built. ISPs expect consistent sending patterns. A sudden surge in volume after a long period of inactivity will be treated similarly to sending from a brand new, unwarmed IP, likely leading to deliverability issues.

For larger senders, it's often beneficial to separate your email streams using dedicated IP addresses for different types of mail, such as promotional and transactional. This helps isolate the reputation of each stream. For instance, if your promotional emails encounter issues, your critical transactional emails might remain unaffected. Using subdomains created under your top-level domain (TLD) for different sending purposes can further enhance this separation and allow for more granular reputation management.

Strategies for consolidating and warming

When consolidating platforms and warming a new IP, a strategic approach is to begin with your most engaged audiences and highly-engaged triggered emails. For example, using your welcome flow journey for the initial sends on a new IP is an excellent strategy. Welcome emails typically have high engagement rates and allow for batched, controlled volumes throughout the day or week. This consistency and positive engagement are precisely what ISPs look for during the warming phase.

The key is to control the volume, starting very small on day one and gradually increasing it. Ensure your ESP allows you to cap daily sending volumes from the new IP. This prevents accidental over-sending that could harm your reputation. If you're managing inconsistent bulk email sending volumes, a consistent, incremental approach is always best.

Here’s a breakdown of considerations for effective consolidation and warming:

Before migration

Audit existing tools: Assess the quality and performance of each email tool you currently use. Identify campaigns with high engagement and those with poor metrics.
Clean your lists: Remove inactive subscribers, bounces, and known spam traps from all lists. This ensures you only migrate a healthy, engaged audience.
Verify authentication: Ensure your SPF, DKIM, and DMARC records are correctly configured for your existing domains and subdomains before migrating.

During and after migration

Phased migration: Move highly engaged, triggered emails first, followed by newsletters or promotional sends with a conservative ramp-up plan.
Monitor engagement: Keep a close eye on open rates, click-through rates, bounces, and complaint rates. Any sudden drops or spikes indicate issues.
Adjust sending pace: Be prepared to slow down or pause sending if you observe negative metrics or high bounce rates during the warming period.

Monitoring and maintaining deliverability

Once your IP is warmed and you've consolidated your sending platforms, continuous monitoring is paramount. Your sender reputation is dynamic, constantly influenced by your sending behavior and recipient engagement. Neglecting it can quickly lead to deliverability issues.

I always recommend regularly checking your IP against various email blocklists (or blacklists). Being listed on a blocklist can severely impact your deliverability, causing emails to be rejected or sent straight to spam. There are many public blocklists, and some ISPs maintain their own private ones. Knowing what happens when your IP gets blocklisted helps you respond quickly.

Beyond blocklist monitoring, pay attention to feedback loops (FBLs) and Postmaster Tools provided by major ISPs like

Outlook. These tools provide insights into your sending reputation, spam complaint rates, and delivery errors, helping you proactively address potential issues before they escalate. Regularly analyzing Google Postmaster Tools data is a critical practice for every email marketer.

Key metrics to monitor

Spam complaint rate: A high rate indicates recipients don't want your emails, leading to blocklists.
Bounce rate: High hard bounces suggest a poor quality list, while soft bounces can indicate temporary issues.
Engagement metrics: Open and click rates reflect recipient interest and are crucial for positive sender reputation.
Blocklist status: Regular checks against major public and private blocklists are essential.

An IP warming schedule example

Here's a detailed example of a gradual IP warming plan:

Day	Volume Target	Audience Focus	Email Type
1-3	500-1,000	Most engaged subscribers	Welcome series, transactional
4-7	1,000-5,000	Recently engaged	Key transactional, highly-anticipated updates
8-14	5,000-20,000	Active subscribers	Regular newsletters, marketing campaigns
15-30	20,000-50,000+	Broader engaged audience	Full marketing campaigns, less frequent sends

This schedule is a general guideline. Actual volumes and durations may vary based on your list size, engagement levels, and the specific ISP you're sending to. Always prioritize quality over quantity during this critical phase.

Views from the trenches

Best practices

Start your IP warming with highly engaged transactional or welcome flow emails to build positive reputation quickly.

Segment your audience by engagement and gradually introduce less engaged segments to the new IP.

Monitor key metrics like open rates, click-through rates, and complaint rates daily during the warming period.

Ensure your DNS records (SPF, DKIM, DMARC) are correctly configured for your new sending IP and domain.

Have a ramp-up plan but be flexible, adjusting send volumes based on real-time deliverability data and ISP feedback.

Common pitfalls

Assuming a previously warmed IP stays warm if it has been idle for several weeks or months, it needs re-warming.

Sending large, one-off batches of emails from a new IP before it's properly warmed, leading to blocks.

Ignoring domain reputation and focusing solely on IP reputation; both are critical for deliverability.

Not cleaning your email lists before migration, bringing over bad addresses that hurt your new IP’s reputation.

Lacking a consistent sending pattern; sudden spikes or prolonged inactivity can trigger spam filters.

Expert tips

Consider segmenting your IPs (e.g., transactional vs. marketing) if you have high volume to isolate reputation.

Use subdomains for different email streams (e.g., marketing.yourdomain.com, transactional.yourdomain.com) for better control.

Engage with ISP postmaster tools for detailed insights into your sending reputation and potential issues.

If budget is a concern for professional re-warming, leverage your highest engagement flows for a self-managed re-warm.

Prioritize recipient engagement and content quality; these are paramount in building and maintaining trust with ISPs.

Expert view

Expert from Email Geeks says that an IP alone isn't the sole factor for reputation; the domain carries significant history with most providers. Successful consolidation often relies on good practices and a prepared reduction in volume to acclimatize ISPs to new infrastructure, building on consistent user interaction.

2018-11-06 - Email Geeks

Expert view

Expert from Email Geeks indicates that an IP that has been quiet for one to two months definitely needs rewarming, even if it was previously warmed.

2018-11-06 - Email Geeks

Final thoughts on consolidation and warming

Consolidating email sending platforms and warming up a new IP address is a strategic move that can significantly improve your email deliverability. It's a journey that demands patience, meticulous planning, and continuous monitoring, but the benefits of a strong sender reputation and efficient operations are well worth the effort. By focusing on quality, audience engagement, and adhering to best practices for IP warming, you can successfully navigate this transition and ensure your emails consistently reach their intended inboxes.

Remember, the goal is not just to send emails, but to deliver them effectively. A well-executed consolidation and IP warming strategy lay the foundation for long-term email marketing success.