# When Should You Consider an Email Warm-up?

Email warmup is not just an essential step when you migrate from another email provider to Batch, with a new subdomain or set of IPs.

It is common to re-warm an IP or subdomain throughout its lifespan, in a wide variety of situations. 

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Here are the cases where you should consider warming up or "re" warming up your sending domain:

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{% tab title="Case 1: Migrating to Batch" %}
If you are migrating to Batch, then you are probably using different sending IPs or sending domains you will need to warm-up.

Senders typically perform an email warm-up, especially for a new pair of sending subdomain/IP addresses during a migration to a new email provider, to **progressively build trust** with inbox providers.

We have documented the whole warm-up methodology for subdomain & IP addresses here: [subdomain & IP warm-up methodology](https://doc.batch.com/guides-and-best-practices/email-deliverability/domain-and-ip-warm-up).
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{% tab title="Case 2: New subdomain or IP" %}

### → New subdomain <a href="#h_ed29719200" id="h_ed29719200"></a>

A warm-up is also required when you start using a new subdomain, to handle transactional messages for example ([see our recommendations here](https://doc.batch.com/guides-and-best-practices/email-deliverability/email-authentication-and-sending-structure/sending-infrastructure-best-practices)).

Even with high email volume on your current shared or dedicated IP, the new subdomain needs to build its own reputation. Inbox providers value IP and sending [domain reputation](https://doc.batch.com/guides-and-best-practices/email-deliverability/getting-started-with-email-deliverability) in different ways, and some may not fully leverage the IP's existing reputation.

If your IP address **already has a strong reputation**, and the subdomain you are planning to warm-up will not send large volumes of emails, you can **try starting with larger batches of emails**, instead of starting with a batch of 200 emails (see our [recommended warm-up schedule here](https://doc.batch.com/guides-and-best-practices/email-deliverability/domain-and-ip-warm-up/step-4-estimate-your-warmup-target)).

### → Introducing a different sending IP <a href="#h_9818911f2d" id="h_9818911f2d"></a>

A domain warm-up is always required when:

* **IP switch**: Switching from one sending IP to another, which should remain a rare situation.
* **Additional IP address**: When adding a new dedicated IP address to your sending pool.
  {% endtab %}

{% tab title="Cas 3: Rewarming a subdomain / IP" %}

### → Planned volume increases <a href="#h_d2992af437" id="h_d2992af437"></a>

Inbox providers often value sending regularity and stable volume for sending domains/IPs, to detect suspect patterns that require protecting their users. Take a look at major inbox providers guidelines to know more on that part (see "Increase sending volume slowly", in [Google's sender guidelines](https://support.google.com/a/answer/81126?hl=en))

This is why every substantial change in the volume of sent emails/day should be implemented progressively, following our [recommended warm-up schedule](https://doc.batch.com/guides-and-best-practices/email-deliverability/domain-and-ip-warm-up/step-4-estimate-your-warmup-target).

### → Bad sending permanence / restarting after a break <a href="#h_8f94829793" id="h_8f94829793"></a>

For senders restarting after a break or with a bad sending performance, consider a brief subdomain warmup. While not as extensive as a new subdomain warmup, avoid sending large email volumes initially.

Start low, engage high:

* Resume sending with lower volumes (1-2 steps below previous, [see scale here](https://doc.batch.com/guides-and-best-practices/email-deliverability/step-4-estimate-your-warmup-target#warm-up-timeline-example))
* Focus on highly engaged users initially.

### → Significant Sending Changes

Inbox providers value consistency.

Sudden changes in sending patterns or new content can raise red flags.

Consider executing a short warmup when you:

* Implement a new tracking domain for email analytics.
* Introduce a completely redesigned email template or drastically change the structure of your emails.
* And more.

By proactively warming up your sending reputation, you can minimize email delivery disruptions and ensure your messages reach your intended audience.
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