IP warming attempts to establish a positive sender reputation from an IP address that has little to no recent sending history. Establishing a good reputation before sending a high volume mailing is recommended because if an IP address’s reputation is not in place (i.e., “warmed”), email receivers may classify the messages as spam and block them.

There is no set method to guarantee a positive sender reputation, but there are some steps you can take to prevent your messages from being marked as spam.

Stagger your mailing

One critical step when sending from a new IP address is to slowly introduce mailing traffic to receivers. If your list is more than 100 subscribers but less than 10,000, spread out the mailing over a few days. If the list is larger than 10,000 recipients, send over the course of a week or more (the "distributed" option allows easy control of these functions).

After you have established your reputation, continue to send at a regular, consistent volume. If there is a spike or dip in volume, this may act as a spam trigger. Remember, receivers like predictable sending patterns.

Additional IP warming considerations

The following actions can establish a good reputation:

• Authenticate your sending domain(s) through our platform before sending your first mailing.
• Create a group that contains your most recent engaged subscribers (those that have been sent an email within the past three months and have had open/click activity).
• Ensure that your list contains only subscribers who have opted in to receive the mailing (if necessary, remove opt-outs and unsubscribers).

After you start sending, check your mailing reports regularly to see if there are any blocks or bounces. If you are seeing less than desirable results, you may need to slow your sending volume and frequency and troubleshoot (look at bounces, domain blocks, unsubscribe reasons, complaints, and content).

If you are noticing positive results in your reporting, you may slowly increase your daily send rate.

Example scenario

One of the best ways to understand the best practices for building a positive sender reputation is following a step-by-step example of staggered mailing. Below is an example of how you might schedule your mailing to a list of 10,000 recipients.

Remember, this is only an example; following this pattern does not guarantee a positive reputation. However, if you monitor your delivery numbers (blocks, bounces, unsubscribes, etc.) with each day’s mailing, you have a better chance of establishing and keeping a good standing with different email receivers.

• Day 1 - Send a mailing to 1,000 of your most engaged subscribers (make sure that they have received a mailing from your organization within the past three months). Use the “distributed” option with this mailing to send it over a 24-hour period.
• Day 2 - View your mailing activity report to see if you are experiencing any blocks or bounces from your first send. If not, increase your next mailing to 2,000 recipients and again use the “distributed” option to send your mailing over a 24-hour period.
• Day 3 - View your mailing activity report (as above). If your statistics are good (few or no bounces/blocks), increase your send to 3,000 recipients and use the “distributed” option to send your mailing over a 24-hour period.
• Day 4 - View your mailing activity report (as above). If your statistics are good (few or no bounces/blocks), send to your remaining 4,000 recipients and use the “distributed” option to send your mailing over a 24-hour period.
• Day 5 - Based on your delivery results from your mailings, decide whether to send at your planned volume. Remember, it is a best practice to continuously check your delivery numbers for each mailing and immediately address any issues. Additionally, always use the “distributed” option to increase your chances of delivery.