Amazon Simple Email Service
Developer Guide

Warming Up Dedicated IP Addresses

When determining whether to accept or reject an email, ISPs consider the reputation of the IP that sent it. One of the factors that contributes to the reputation of an IP is whether the IP has a considerable history of sending high-quality emails. ISPs that receive mail from a new IP that has no history tend to be more cautious about accepting mail from it. This manifests as throttling (soft, transient) bounces, but can also result in rejection (hard) bounces, as well as putting your mail in the junk folder until the IP establishes a good reputation by sending a steady stream of high-quality mail.

You should therefore gradually increase your sending through a new dedicated IP before you use it to its full capacity. This process is called warming up the IP. You warm up an IP by using the following three principles:

  1. Start small.

  2. Measure results.

  3. Make corrections.

Ideal IP warm-up times vary by ISP and recipient. It takes a minimum of 14 days to establish some level of positive reputation with some ISPs; it can take up to 6 weeks for many ISPs. When warming up a new IP, you should send emails to the users who engage with you the most to ensure that your complaint rate is low.

For best results, you should carefully examine your bounce messages and send less email if you receive a high number of IP blocking or throttling responses. For information about how to monitor your bounces, see Monitoring Your Amazon SES Sending Activity.

By default, Amazon SES automatically warms up your dedicated IP addresses based on a predefined warm-up plan.

Automatically Warm up Dedicated IPs

Amazon SES controls the amount of email that can be sent through an IP address. Amazon SES uses a predefined warm-up plan that indicates the maximum number of emails that can be sent daily through an IP address to ensure the traffic is increasing gradually over 45 days.

The automatic warm-up feature is enabled by default. When it is enabled, all new dedicated IP addresses you lease from that point will be automatically warmed up. The IPs you are currently leasing and using from your account can’t be warmed up automatically with this feature.

If you are a new or an existing customer and you request dedicated IPs for the first time, Amazon SES will automatically start to warm up your dedicated IPs. During this time, Amazon SES will initially send emails through both your dedicated IPs and shared IPs. The emails that you send beyond the daily pre-planned warm-up plan will be delivered using shared IPs. After your IPs are warmed up, Amazon SES will send emails only through your dedicated IPs, and the maximum number of emails you can send is dictated by your approved daily email quota. This process enables you to continue sending at your allocated daily quota.

If you are an existing customer and you request additional dedicated IP addresses, Amazon SES will automatically start to warm up your newly received dedicated IPs. Amazon SES will distribute the emails you are sending through both your already fully warmed up IPs and the newly received dedicated IPs, and will not send emails through shared IPs as you are using dedicated IPs to send your emails.

If you disable this feature, you must control the amount of email that can be sent through an IP address manually and will be responsible for gradually warming up the dedicated IP addresses.

After you successfully warm up your dedicated IP addresses, we recommend that you send at least 50,000 emails per day from each dedicated IP address in order to maintain a positive reputation. To avoid having your email rejected or throttled by ISPs, avoid sending a high volume of emails immediately after the warmup process has completed; instead, you should gradually increase the volume of email you send over time.