Email: IP Warmup

IP warming is the process of slowly increasing sending volume to help inbox providers determine a sending reputation on a new dedicated IP address.

Inbox providers will be weary until they can determine a positive sending reputation which is why the warmup process can take four to six weeks depending on the level of engagement and your target volume.

Your sender reputation

As your email volume gradually increases, the inbox provider's machine learning algorithms will determine your sender reputation based on the following rates:

  • Bounce per sent
  • Delivered per sent (delivery rate)
  • Marked as spam
  • Unsubscribes per sent
  • Unique click
  • Unique open

The more conservatively you ramp up your daily volume, and the higher the delivery rate and user engagement, the better. Note that sender reputation is evaluated based on a 30-day rolling calendar.

IP warmup targeting 

Engagement, in addition to increasing volume, is a key factor in helping inbox providers determine your sending reputation.

  1. Begin by targeting your most engaged subscribers. (All Users > Lifecycle > Last Active).

  2. Choose a mailing that your subscribers are expecting (e.g. newsletters and product updates) with relevant content. Inbox providers look towards recipient engagement to determine a sending reputation and inbox placement. Customize email mailing to encourage positive recipient engagement not negative.

    Positive Engagement is more likely to lead to timely acceptance and/or inbox placement. Positive Engagement includes:

    • Opening
    • Clicking
    • Starring
    • Foldering
    • Labeling
    • Getting added to address book

    Negative Engagement can lead to poor Sending Reputation resulting in Temporary Deferrals, Hard Blocks, Blacklists and/or Spam foldering. Negative​ Engagement includes:

    • Marking as Spam
    • Deleting without reading
    • Auto filtering to the spam folder
    • Unsubscribing
    • Not opening
  3. Expand last active audience by send. Large spikes in volume could result in temporary deferrals by inbox providers. Expanding volume by send  could help identify the population engaging negatively with the mailing.

Take a look at our Email Best Practices for more tips to improve and maintain delivery rates and sender reputation.

Warm-up schedule

Leanplum’s email service provider (ESP), SendGrid, recommends the following daily email schedule to warm up an IP address. Your Customer Success Manager can help you with this process, but if you prefer to do it yourself, be sure to follow this schedule when you start sending emails.

day emails/day
1 50
3 500
4 1,000
5 5,000
6 10,000
7 20,000
8 40,000
9 70,000
10 100,000
11 150,000
12 250,000
13 400,000
14  600,000
15  1,000,000
16  2,000,000
17  4,000,000

2x sends daily

Warming up your IP with random user buckets

Depending on your number of Daily Active Users, one way to limit your emails per day is to add User Buckets to your Target. Each user is randomly assigned a bucket between 0 and 999, making it easy to segment your target into smaller groups and gradually ramp up email sends.

  1. In the Users page, click Add Segment to open the dropdown, then select User Bucket.
  2. Enter a range of two numbers after "User bucket is between", or select a different operator by clicking on “is between.” For example, the target "User bucket is between 0 and 250" should include roughly one-quarter of your users (250/999).
  3. Hit the search button to see your results, which will include an estimate of the number of users in your segment. Adjust the User Bucket and target until the user estimate matches the recommended volume from the warm-up schedule.
    Tip: You may also want to add segment criteria for "User attribute email is set" AND "Unsubscribed from all marketing emails is false" to ensure that your user count only includes users who can receive emails. Save this segment to make it easy to use again later.
  4. Click "Send a message to matching users" to pre-load this target into the message composer, then select Email as your message type and customize your content.
  5. For the next email message (tomorrow), repeat these steps but choose a different range of buckets that includes the number of users recommended for the next day of the warm-up schedule.
    Note: User buckets are persistent, meaning that the users in each bucket will remain in their bucket throughout their experience with your app.
    So if you send buckets 1-5 an email, then send buckets 1-10 an email the next day, the users in buckets 1-5 will receive both emails. Keep this in mind when choosing user buckets, and try not to send the same group of users too many messages.

Note: If you have a very large user base, User Buckets may not be able to limit your email list to a small enough group when starting out. In that case, you can use other targeting techniques to limit the number of email recipients.

What to expect

During IP warming you should expect the following:

  • You may reach your desired Delivered per sent rate up to 72 hours after send. AOL, Microsoft, Comcast, Yahoo and Gmail may be temporarily deferring the mail. Temporary deferrals are common.
  • Our email service provider will continue to retry sending for 72 hours. After this time, the mail will fail out, affecting your Delivered per sent rate.
  • Allow 24-36 hours for recipients to engage to determine your true reporting metrics.
  • If your desired Delivered per sent rate is not achieved, pause your IP warming schedule for 24 hours to allow more mail to get accepted by the inbox provider.
  • If pausing your IP warming schedule does not resolve the low Delivered per sent rate, segment out your less active population with a separate more personalized mailing.
  • The number of hours it takes to reach your desired Delivered per sent rate should improve after each send.

Check out our Top Reporting Metric Issues.

Other resources

Here are some other things to consider when starting out:

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