Do I need to warm up my domain if I'm migrating to a new ESP but keeping my existing sending domain?

Yes, it is generally necessary to warm up your domain even when migrating to a new ESP with the same domain. While your domain retains its historical reputation, the new sending infrastructure (IP addresses, ESP setup) is unfamiliar to mailbox providers. A gradual warm-up helps them recognize your legitimate sending patterns from the new source, preventing deliverability issues. This is especially true even if you're on shared IPs, as explained in articles about warming up on shared IPs .

What's the difference between warming up on shared IPs versus dedicated IPs?

If you're using dedicated IPs, a full IP warm-up is crucial. These IPs are new and have no sending history, so you must gradually increase your sending volume to build a positive reputation. For shared IPs, the underlying IPs are typically pre-warmed by the ESP. However, you should still implement a gradual ramp-up for your domain to establish its sending patterns on the new shared IP range.

What happens if I skip the domain warming process when migrating ESPs?

Skipping the warm-up can lead to severe consequences, including emails landing in spam folders, increased bounce rates, and even getting your domain or IPs placed on an email blocklist. This harms your sender reputation and can be difficult to recover from, impacting all future email campaigns.

Do I need to update my DNS records when I move to a new ESP?

Your ESP should provide specific DNS records (SPF, DKIM, and possibly DMARC) that need to be updated in your domain's DNS settings. This ensures that mailbox providers can authenticate your emails coming from the new ESP. Correct configuration of these records is a fundamental part of maintaining email deliverability .

How long does domain warming usually take?

The duration of the warm-up period varies based on your list size, sending frequency, and engagement levels. It typically ranges from a few weeks to several months. Start with small volumes to your most engaged subscribers and gradually increase over time, while closely monitoring your deliverability metrics. Tailoring the IP warm-up strategy to your specific needs is key.

Is it necessary to warm up a domain when migrating to a new ESP? - Sender reputation - Email deliverability - Knowledge base

Migrating to a new email service provider (ESP) can feel like a fresh start, but it often comes with a critical question: Do I need to warm up my domain? It's a common area of confusion, especially when an ESP suggests it might not be necessary. While some believe the rules have relaxed, my experience tells me that a cautious approach is almost always best for maintaining strong email deliverability.

The core of the issue lies in how mailbox providers assess your sending reputation. When you switch ESPs, even if you keep the same sending domain, you're introducing new sending infrastructure, which includes new IP addresses and possibly new sending patterns. This change can raise red flags with services like

Gmail,

Outlook, and

Yahoo. Domain warming helps build trust with these providers, ensuring your emails reach the inbox and avoid the spam folder or being placed on an email blacklist (or blocklist).

Domain and IP reputation explained

Before diving deeper, it's helpful to understand the nuances between domain and IP reputation. While often discussed together, they refer to different aspects of your sending identity and how mailbox providers perceive your email program. Both contribute significantly to your overall sender reputation and, consequently, your email deliverability.

Your domain reputation is tied to your brand's sending history and how recipients interact with your emails, regardless of the underlying IP address. Mailbox providers track engagement metrics such as opens, clicks, unsubscribes, and spam complaints associated with your domain. A strong domain reputation signals to providers that your emails are valued by recipients, making them more likely to land in the inbox.

Conversely, IP reputation is linked to the specific IP address from which your emails are sent. New IP addresses have no history, so they are considered 'cold.' Sending high volumes from a cold IP can trigger spam filters, as it might appear suspicious. IP warming, therefore, is the process of gradually increasing email volume from a new IP address to build a positive sending history.

Domain reputation

Brand association: Directly linked to your brand's sending domain, e.g., yourcompany.com.
Long-term: Builds over time through consistent, positive engagement.
Recipient interaction: Influenced by opens, clicks, spam complaints, and unsubscribes.
Key for trust: Mailbox providers increasingly prioritize domain reputation.

IP reputation

Technical association: Linked to the numerical IP address used for sending.
Short-term: Can fluctuate based on recent sending volume and behavior.
Sending behavior: Influenced by sending volume, consistency, and bounce rates.
Infrastructure: New IPs are cold and need warming to build trust.

Why domain warming is always necessary

Despite what a new ESP might tell you, domain warming is almost always a necessary step when migrating. Even if your domain has a stellar reputation from your previous ESP, moving it to a new platform means you're now sending from different IP addresses, even if they're shared. Mailbox providers will see this new sending pattern and evaluate it, which can impact your inbox placement.

If you skip the warming process and immediately send high volumes, you risk triggering spam filters and getting your domain or the new IPs listed on a blocklist (or blacklist). This can severely damage your sender reputation, leading to poor deliverability, where your emails either land in spam folders or are rejected outright. It's a risk that's simply not worth taking for your email program's health.

I've seen many cases where skipping domain warming (even on shared IPs) has led to significant deliverability issues. For example, Al Iverson shares a compelling case study on domain warming gone wrong, illustrating the severe consequences of not following proper warming protocols.

The risk of skipping domain warming

When you migrate to a new ESP without proper domain warming, even if you keep the same domain, mailbox providers might perceive the sudden shift in sending patterns as suspicious. This can lead to your emails being flagged as spam, affecting your sender reputation and leading to a significant drop in deliverability. Always prioritize a gradual warm-up to mitigate these risks.

Shared versus dedicated IPs

The type of IP address your new ESP provides also influences your warming strategy. Moving to shared IPs at a new ESP is generally less complex than moving to dedicated IPs, but it doesn't mean you can skip warming entirely.

With shared IPs, you're leveraging the collective reputation of other senders on those IPs. While this can offer some protection, your domain's reputation is still paramount. You should still implement a gradual ramp-up of your sending volume to introduce your domain to the new shared IP range. Conversely, dedicated IPs have no prior sending history, requiring a full and meticulous IP warming process to build trust with mailbox providers. This typically involves a structured schedule of increasing volumes over several weeks. You can find more details on best practices for migrating ESPs with subdomain and IP warmups.

It's also important to consider the guidance from major providers. For instance, Microsoft's guidance on warming emphasizes the necessity of warming up your domain alongside your ESP's IP addresses, whether the domain is new or existing. This reinforces the idea that even with shared IPs, a gradual introduction is crucial.

Factor	Shared IP Migration	Dedicated IP Migration
IP warm-up needed?	Generally less critical, as IPs are pre-warmed, but still beneficial to monitor.	Essential. New IPs have no reputation and require a full warm-up schedule.
Domain warm-up needed?	Yes, always. New infrastructure for your domain needs to be recognized.	Yes, always. Even a pre-existing domain needs to build trust on new IPs.
Risk of issues	Lower for IP, but significant if domain volume isn't gradually introduced.	High for both if warm-up is skipped, leading to blacklisting or spam folders.

Best practices for a smooth migration

To ensure a smooth transition and protect your sender reputation, I recommend a structured approach to domain warming when migrating ESPs. This involves more than just sending emails, it's about strategic volume increases and diligent monitoring.

Start by gradually increasing your email volume, targeting your most engaged subscribers first. This sends positive signals to mailbox providers. Continue to scale up your volume incrementally, closely monitoring your delivery rates, bounce rates, and spam complaints. Leverage tools like Google Postmaster Tools or your new ESP's reporting to track performance and adjust your sending plan as needed.

Finally, make sure your email authentication protocols, particularly SPF, DKIM, and DMARC, are correctly configured for your new ESP. These DNS records are crucial for verifying your identity as a legitimate sender and play a significant role in deliverability. I find that this kind of proactive planning for your email sending after migrating can make all the difference.

Example DNS records after migration

After migrating to a new ESP, you will need to update your DNS records to reflect the new sending infrastructure. This typically includes:

SPF record: Include the new ESP's sending IPs or domain.
DKIM record: Add the new DKIM keys provided by your ESP.
DMARC record: Ensure it's configured to monitor your email streams.

Example DNS records after ESP migrationtext

v=spf1 include:_spf.newesp.com ~all
senderkey._domainkey.yourdomain.com TXT "v=DKIM1; k=rsa; p=YOURPUBLICKEY"
v=DMARC1; p=none; rua=mailto:dmarc@yourdomain.com; ruf=mailto:dmarc@yourdomain.com; fo=1

Ensuring your deliverability

The transition to a new ESP is a critical moment for your email program. While the temptation to "just send" can be strong, especially with assurances from your new provider, it's almost always in your best interest to err on the side of caution.

Prioritizing a strategic domain warming (and IP warming, if on dedicated IPs) process will safeguard your sender reputation, ensure high inbox placement rates, and ultimately protect your valuable email channel. It's an investment in your long-term deliverability success.

Views from the trenches

Best practices

Always follow a gradual warming schedule even if the ESP says it is not needed.

Start by sending to your most engaged subscribers to build positive signals.

Monitor your deliverability metrics closely during the migration and warm-up period.

Common pitfalls

Assuming that shared IPs mean no warming is needed is a common mistake that causes deliverability issues.

Not setting up or verifying your DNS records (SPF, DKIM, DMARC) with the new ESP.

Ignoring early signs of deliverability problems, such as increased bounce or spam rates.

Expert tips

Focus on domain warming even when on shared IPs, as domain reputation is increasingly important.

If moving from a good ESP, consider a slower warm-up to allow filters to adjust.

Continuously monitor your sender reputation and adjust your sending strategy.

Expert view

Expert from Email Geeks says that migrating platforms, or even from shared to dedicated IPs, will always require warming.

2022-07-12 - Email Geeks

Marketer view

Marketer from Email Geeks says that it is concerning if an ESP states that warming is not needed, especially when moving to shared IPs, as this can lead to deliverability issues.

2022-07-12 - Email Geeks