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How to warm up your IPs and domain

If you use email to contact your clients, you probably know it’s important to manage email responsibly and be careful not to risk your sender reputation. In this article you’ll find out why it’s important to warm up your IPs and domain and what warm-up plan to follow in order to achieve the best results quickly and efficiently.

The fundamentals of warming up your IPs and domain

Internet Service Providers (ISPs) such as Gmail, Hotmail or Yahoo! do a really good job of protecting us from malicious or unsolicited emails. If they spot anything unusual, they might send your messages to a spam box or even block them completely.

But even if you don’t do anything suspicious, you need to gain their trust before they let you send email in greater volumes. A new IP will have no mailing history and ISPs simply don’t know whether to assume you’re a legitimate sender or not. Just to be on the safe side, they choose not to trust until proven otherwise.

However, IP alone is not enough to send email. You also need a domain to send it from and here it's pretty much the same story. A new domain has no sending reputation and building and maintaining it slowly is just as important as it is in case of IPs.

This is why you must start sending a low volume of emails to begin with, and gradually and systematically increase the amount of emails over a period of time. This way, ISPs will be able to see whether or not you are a sender that your recipients trust and, if they do, you will be allowed to send a greater number of messages the next time.

Over time ISPs learn to recognise your sending habits and the content of your messages. Steady open rates that indicate the recipients have been engaging and are happy to see your emails is the key to let your messages land in your clients’ inboxes. But this requires patience and discipline.

What happens if you skip the warmup process

If you’re impatient and ramp up the number of emails you send too quickly, you’ll probably see delivery or inbox placement problems even if you use an email list that is as healthy as can be. Think of it as pre-workout warm-up exercises that are crucial to get your muscles ready for activity. There’s no way around them and if you skip the warmup, you could be at risk for a serious injury.

During the warming process, ISPs are very sensitive to your sending behaviour. They set receiving limits until you meet their standards. Only if you earn a good sender reputation, will you see consistent higher inbox placement rates and be able to send your normal volumes with this particular domain and IP address or addresses.

Why it’s essential to warm up both the IP and the domain

We’ve already established that when you add a fresh domain to your account, it has zero sending history and needs warming up to acquire a good reputation with ISPs. It means that you can’t email your entire list from day one or you run the risk of burning the domain and you probably won’t be able to rescue it. You must start with a limited volume of emails and increase it gradually over time.

On the other hand, you might have an already established domain that you used for sending a great number of emails. So, you may think bringing such a domain to Coresender is good enough to let you start sending a lot of emails right away.

Even if such a domain has a long history of sending high volume of emails elsewhere, now you’ll be using different IPs. This is a new set of domain+IPs that has no sending history. For ISPs’ spam filters this is a significant change. This is why it’s better to start slow and see what happens in terms of deliverability before drastically increasing the number of emails you send.

How to go about warming up IPs and domains

Building your sender reputation requires time and effort, but just like in real life, it can easily get ruined in no time at all and is even harder to repair afterwards.

You need to warm up both the IP and the domain gradually to establish a good reputation. Break your lIst into small segments and start sending emails at regular intervals and gradually but consistently increase the sending volume. It usually takes about a month before the warmup process is complete and you can begin using the system to its full capacity. This may seem long, but it’s an investment that is really worth the patience and the effort.

The warmup plan to follow

A good warmup plan is half the battle. If you follow it closely and gradually increase the amount of emails you send, you’ll be able to monitor the engagement, remove inactive recipients and to react quickly in case of a problem. You can optimise your sending program and slow down or adjust it accordingly.

Here’s what we’ve found to work best for most of our clients.

IP Warmup Schedule

(The number of messages sent each day to get the best warmup results)

Day Daily volume

This is an example warm-up schedule and in your case adjustments may be required due to the list age and hygiene, user engagement, domain age and the kind of content you send.

If you think you’re not like “most of our clients” or simply would like to ask for help, feel free to contact us at with a short description of your mailing list and the type of content you’re sending. We’ll be happy to suggest the most efficient warm-up schedule for you.

Some issues are to be expected anyway

If you follow a good warm-up plan, your chances of strong deliverability will increase substantially. This, however, depends on the content you send, the list hygiene, the engagement of your recipients and there are certainly no guarantees of success.

You’ll probably have some issues in the beginning, no matter how cautious you are. This is nothing out of the ordinary, so please don’t be alarmed. Stick to the plan and make necessary changes if you encounter problems on the way.

Segmenting your list at random is surely not the best practice to follow. As always, the first impression makes all the difference. Therefore, it’s more than a good idea to begin sending messages to your most engaged users first, keep your list clean and avoid unexpected volume increases at all costs.

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