In our last post, we broke down the first of nine deliverability tips email marketers need to make sure messages land in the inbox.

We started with a clear signup/opt-in process, a welcome message/series, and an important look at the difference between delivery and deliverability. Today we’ll break down the next three email deliverability tips in our series!

4) Warmup new IPs/domains

Whether you’re looking to send from a new domain or maybe just increasing the volume from your current mailstream through additional IPs, it’s important that you slowly warm up the traffic. 

Taking a gradual approach is recommended, as it’s a lot easier to build up a good reputation than to try to dig out of the spam folder due to sending too much volume initially. 

With our Automated IP Warmup, we’ll do the heavy lifting for you. If you choose not to use this method, IP warming is the process of onboarding a new IP address by gradually increasing the volume of emails sent from it over a period of time. IP warming is just one of many pieces in the puzzle that is email deliverability, and it’s one of the single most important pieces to consider. 

Given the right circumstances, IP warming, or the lack thereof, can be the single biggest contributing factor to your poor email deliverability. IP warming is the best way to build up a positive reputation, but it’s not as simple as it seems. 

You will want to follow these important email sending best practice tips:

  • Send to your most highly engaged people, the high-engagement campaigns that have done well in the past. The goal during your warm-up process is to send to subscribers who are least likely to complain and bounce. This would include those that have opted-in most recently and are consistent openers/clickers.
  • During the warm-up phase, the more consistent you are with volume, frequency, complaint, and bounce levels, the faster you will establish a positive sending reputation. If you send infrequently – anything less than weekly – it will take more time to build a positive sender reputation.

It is important to monitor your metrics and adjust the plan accordingly during the warm-up period. Remember, take it slow, be patient, send to your highly engaged, and don’t panic.

5) Use different IPs/subdomains for different email deliverability streams

An email stream is a way of identifying similar groups of emails. Streams are typically grouped based on the purpose of the email. 

For example, transactional emails are time-sensitive messages that are sent as a response to a recipient action, such as a request for a password reset or a confirmation of purchase. 

Editorial or subscription emails typically contain informative content and the recipient is expecting to receive the email at a regular cadence. Promotional or marketing emails are advertisements for a product or service and can be sent at regular or irregular intervals, and the recipient may not want all of the emails.

These different email streams tend to develop different reputations based on how the mailbox provider evaluates the content and how the recipient interacts with the email. As a result, the sending IP address, the domain, and the subdomain are all assigned a reputation. The result of this reputation is that email can be delivered, delayed, or even blocked. 

Thus, it is important to separate transactional and marketing emails on different IP addresses so that you don’t jeopardize the delivery of your time-sensitive content. 

For email streams that are somewhat alike and are sending from the same IP addresses, separating the streams by using different subdomains will help to separate the reputation of your email. Subdomains are also extremely helpful when trying to identify a delivery issue for streams sending on the same IP address as you may find that only certain subdomains are being throttled or blocked. Remember, when creating a subdomain, it should reflect the purpose of the email, such as,, or 

Ultimately, the goal of separating email streams on different IP addresses and/or subdomains is to ensure that your different types of emails all have the best opportunity to be delivered without affecting one another. 

6) Segmentation & Personalization

The key to driving strong engagement rates is precise targeting of category-specific mailings to customers most likely to buy from those categories. By doing this, you also offset the risk of unsubscribes, spam complaints, and those who just ignore your emails from over-mailing non-relevant content.

Segmentation is one of the most effective tactics to engage your email recipients, often resulting in higher opens, clicks, and conversions. Studies have shown that brands deploying highly-targeted email have a read rate 5-10 percentage points higher than those who do less targeting. 

A good start to segmenting your audience is by list pruning to remove the portion of your audience that is not engaging with your messages. Once your non-engaged users are out, you can focus on creating targeted campaigns for your engaged subscribers. Segments can be as large as all users who have subscribed in the last few months, or as small as users who purchased a specific item. Closely examine your data, see how customer segments are engaging, and create personas for your audience to further differentiate one user from another.

When it comes to personalization, try to be a bit creative. While mentioning your recipient’s first names in the subject line is a great attention-getter, there are other options available. By dynamically populating your messages with product references or offering expirations and shipping deadlines, using these deliverability tips will make your emails really stand out to recipients.

Stay tuned for our next post where we’ll break down our final three deliverability tips for email marketers. In the meantime, if you need to catch up on our first three tips you can find them here!

~ SparkPost Deliverability experts, Scot Berggren, Hanna Cabanellas, Tracey Crawford, and Doug Turetzky

Subscribe to Newsletter