Direct Mail:Dedicated IP

Email delivery is complex. Email service providers (ESPs) often set daily sending limits based on the reputation of a sending domain and IP address. Therefore, you should not send large volumes of email from a new domain or a new IP that has not yet established a sending reputation.

The process of building reputation by gradually increasing daily sending volume is known as a warm-up.

DirectMail offers two warm-up modes:

1. Manual warm-up

When you purchase a new dedicated IP, the default warm-up mode is manual warm-up. You must control your daily sending volume and gradually increase it until you reach your target sending volume.

2. Automatic warm-up (recommended)

If a dedicated IP has not yet met the warm-up criteria, the system automatically allocates a portion of your sending traffic to the dedicated IP channel for warm-up. This process currently covers major ESPs such as Gmail, Yahoo, Outlook, and iCloud. The entire process is automated and requires no manual intervention.

If your actual sending volume exceeds the daily warm-up threshold, the excess traffic is automatically routed to the shared IP channel for delivery. You can monitor the warm-up progress of your IP in real time in the console.

Comparison of warm-up methods:

If you purchase multiple dedicated IP addresses, you can group them into an ip pool. When you send emails, you can then specify which ip pool to use.

In the upper-right corner of the console, click New IP Pool.

Enter a name for the ip pool and associate your IPs with it. Note that ip pool names must be unique, and each dedicated IP can only be added to one ip pool. The number of ip pools you can create cannot exceed the number of dedicated IPs you have purchased.

A common practice is to create one ip pool for sending marketing emails and another for sending transactional emails.

This approach isolates the reputation of each email type. With this configuration, even if a marketing campaign generates a high number of complaints, the delivery rate of your transactional email is not affected.

You can use one of two methods.

Method 1 (recommended)

In the console, bind a configuration set to your sending address. Once bound, all sending methods for this address automatically use the dedicated IP, eliminating the need to specify the ip pool ID parameter in your send requests. For more information, see Send configuration (configuration set).

Method 2

With this method, you must specify the ip pool parameter with each sending request.

The following examples show the required parameters for each sending method (console, API, or SMTP).

Using the console

When creating a new email sending task, select an ip pool. The system will use the IPs from the selected pool to send the email.

Using API or SMTP

Obtain the ip pool ID (this is not the instance ID or the IP address). See the example code below:

1. View data (ip pool): Displays data only for the specified ip pool. An ip pool can contain multiple dedicated IPs.

2. View data (dedicated IP): Displays data only for the specified dedicated IP.

3. View (warm-up): Displays data only for service providers that support automatic warm-up, such as Outlook, iCloud, Gmail, and Yahoo.

You can estimate the number of sending IPs you need based on your actual sending volume. As a rule of thumb, a single sending IP can typically support a peak instantaneous sending volume of about 100,000 emails.

For business continuity and disaster recovery, we recommend purchasing at least two sending IPs. For example, if the machine bound to a sending IP experiences a failure or hardware fault, having at least two hot-standby IPs allows for automatic failover, ensuring that your services continue without interruption.

When you purchase dedicated IPs, the system balances the new IPs across different availability zones based on your existing IP resources.

If your recipients are in a different region from where your DirectMail service is activated (for example, your service is activated in China (Hangzhou) but your main recipients are in the US or Europe), we recommend purchasing a dedicated IP address in the same region as your primary recipient base. Email service providers consider geographic location when assessing email trustworthiness, and using a local IP address helps build a better IP reputation and avoid restrictions associated with cross-region email delivery.

To confirm the best region-matching strategy or to purchase a dedicated IP in a specific region, you can submit a ticket to contact us.

If fallback is not manually disabled in the configuration set, traffic will automatically switch to the shared IP channel to prevent errors.

A dedicated IP must be warmed up to meet the safe receiving threshold of the target email service provider (the initial threshold is 1,000). When you initiate a sending request, the automatic warm-up feature first delivers mail using the dedicated IP. If the sending frequency exceeds the IP's limit, the system automatically switches to another fully warmed-up dedicated IP or to the shared IP channel. This prevents subsequent emails from failing due to provider-side throttling, eliminating the need for a manual warm-up.

Because using a dedicated IP affects its reputation, it cannot be refunded.