Warm up a sending domain or subdomain

Warming up a domain is an essential step when you start sending emails from a new domain or subdomain.
In this article, we explain why it is important, in which situations it should be implemented, and which best practices to follow to build a good sending reputation and preserve your deliverability.

Why warm up a domain?

When a new domain or subdomain is used to send emails, mailbox providers (Gmail, Outlook, etc.) do not yet have any history or reputation associated with it.

Sending a large volume of emails right from the start can result in your messages being marked as spam, temporary blocking of mailboxes, and the deterioration of your domain’s reputation and of your deliverability.

Domain warming therefore consists of gradually increasing the sending volume in order to build a good reputation with mailbox providers.

When should you warm up a domain?

Warming up is recommended in the following cases:

• Creation of a new sending domain

• Creation of a subdomain

• Resumption of sending after a long period of inactivity

Even if your main domain is already in use, a new subdomain must also be warmed up.

Best practices

For an effective warm-up, start by sending to your most engaged contacts, gradually increase volumes, and monitor open rates, clicks, and spam complaints. Avoid sending to your entire contact database immediately.

Example of a warm-up schedule to get started properly

Here is an example of a gradual ramp-up for your new domain or subdomain.

Then gradually increase the volumes according to the performance of your campaigns.

If performance deteriorates, it is recommended to stabilize or temporarily reduce the volumes.

If you have just configured a new sending domain or subdomain, we recommend planning your warm-up strategy before your first major campaigns.