How to Warm Up a Sending Domain in Critical Impact

Warming up a sending domain is an essential part of establishing yourself as a reputable sender and gaining the trust of ISPs (both Inbox Service Providers and Internet Service Providers). Warming up is essential for a new domain and for a new IP. This process may seem like an extra step between you reaching your subscribers, but any extra time spent here will bolster your likelihood of reaching the inbox of your subscribers.

Warming up your domain is a multi-stage process, starting before you've even sent your first email. Let's take a look at some of the steps you may consider:

1. Establish/Age Your Sending Domain
2. Set Up Sender Authentication
3. Establish an Active Client List
4. Send an "Induction Send"
5. Review (and Continue to Monitor) Send Performance
6. Increase Your Send Size Slowly

1. Establish/Age Your Sending Domain

Although it is exciting to have a new opportunity to start sending, good things come to those who wait. Sending immediately from a new domain can seem suspicious to an ISP. A suspicious ISP may limit the number of emails the would like to deliver from your domain until you have substantial subscriber interaction - a hard thing to do if you are constantly being blocked from delivery or landing in the spam folder.

Letting your domain age at least 30 - but preferably 90 - days is an important step in delivery. This allows ISPs to come to trust your domain and, with the addition of small sends at the right time, will result in a consistent deliverability rate.

2. Set Up Sender Authentication

Sender authentication is not a requirement but it is becoming more and more common to see this as a barrier to delivery if it is missing. Sender authentication is a way of giving your emails a "digital signature" that say the message comes from a source that is okayed by your domain. If you haven't already talked to us at Critical Impact about setting this up for your account, please reach out to us at support@criticalimpact.com to have this enabled if you would like to have this extra layer of security.

3. Establish an Active Client List

Every ESP is different. Here at Critical Impact, we use rules with our dynamic lists to create an interactive clients list. You may have something like this from your previous ESP for subscribers that had opened or clicked more frequently than others. Regardless, you want to send to the most active subscribers for your first sends. This ensures that these sends will have a high open or click rate, which shows ISPs that subscribers want to see your content. This will result in a higher inbox placement rate long-term.

Note: These rules are great if you have already started sending from this domain. You do not want to send to 5,000 subscribers immediately. If you need help warming up from zero sends, please reach out to us at support@criticalimpact.com.

4. Send an "Induction Send"

Once you have your active, most engaged client list selected, you can send this primary send. This is generally no more than 5,000 subscribers. This is a great way to put "feelers" out to see how ISPs as well as your subscribers respond to your message content, subject line, and from address. This delivery rate will inform the pacing of the rest of the warm up.

If you have not sent from this domain at all, I know you don't want to hear it, but you have to send with single digit sends and grow from there.

5. Review (and Continue to Monitor) Send Performance

The initial send will provide a cursory glance into the performance of your sending domain. If your delivery rate is good (≥95%), then we can continue to increase our send size. If you see good delivery rates compared to your previous sends, then you can continue on your current trajectory. If you notice any negative results, you may want to either slow down your growth or review your lists to ensure you are using high quality lists.

6. Increase Your Send Size Slowly

Your second send can be up to 10,000 subscribers if your first was 5,000. From that point forward, you should aim to increase your daily total send size in increments of around 20-25%. If you need to move more quickly than that, you can do so cautiously, but never increase your send size more than 50% over the previous day's total. This speed will likely result in a damaged sender reputation and inbox placement.

With good sending practices and a little patience, you'll get to your full list in no time. There is no limit to a max send size if warmed up properly, so if you need to send to 10 million subscribers a day, you can! You just have to have the patience to get there.