Set up DMARC and see who's sending email using your brand's domain.

Are dedicated IPs important?

It’s been almost five years since I wrote about dedicated IPs being less important as domain reputation increased in importance. Back then, I might have jumped in a bit too soon, but the concept was solid. The direction of domain based reputation with DKIM was starting to happen and the responsibility of ESPs to police their own networks was getting more important. Looking at the same post today it’s nice to see it has really stood up on its own. 

In that article, I mentioned a post from Laura Atkins from Word to the Wise, someone we respect highly and follow when it comes to email and security around messaging. Just recently, she posted a Q&A about the same topic that really shows how much this has changed since 2011. She points out how ISPs are becoming less reliant on IP reputation. More specifically, there are some great points on how to make the best of a shared IP environment, such as:

  • Use your own domain in the DKIM signature. We’ve supported this for a long time, but our latest release of Domain Verification builds on the advantages of DKIM.
  • Take advantage of personalization of the return-path. You can use our custom return-path settings for this, which also helps you align with DMARC policies if you have one (you should).
  • Brand your emails and use consistent design elements. This helps ensure that your emails are easily recognizable by filters as well as recipients so they don’t report them as spam.

These changes toward domain reputation are why we reserve dedicated IPs for only the largest senders, since most senders benefit more from sharing the reputation of many other good senders. Instead, we encourage DMARC alignment, pushing the identity of email streams more toward the domain owner so they can build a portable reputation. 

Earlier this year I had an experience that really illustrated just how much domain reputation matters regardless of the ESP you use. One customer’s emails were consistently being flagged as spam. After looking into it, the problem was that they were sending their bulk and transactional email from the same domain, and their bulk sending was dragging down the reputation of their domain. So their transactional email delivery suffered as well. It's imperative to use different domains for high engagement transactional email and lower engagement bulk promotional email. Even Gmail advises separating the sending domain and IP for different types of email as much as possible. Domain reputation matters.

IP addresses do still matter. It’s up to us as an ESP to police our network and segment our sending. While the major ISPs rely increasingly on domain reputation, the corporate networks and filters still rely heavily on blacklists, screening, and IP reputation. It’s our job to keep our email streams pristine so that domain reputation can stand on top of an excellent IP reputation.

This doesn’t mean that we don’t offer dedicated IPs. There are cases where we will look at traffic and move customers to their own IPs. This could be due to volume, short term delivery or infrastructure issues, testing, or even security policies. We try to make this decision based on the best delivery speed possible for our customers, not as an up sell opportunity. If a customer’s sending justifies dedicated IPs, it’s something we do for free.

Our focus at Postmark is transactional, and while we care about getting to the inbox, we really care how fast we get to the inbox. This is where IP reputation, domain reputation, and core infrastructure all come together. To make this happen we need to give you the tools (DKIM, DMARC) to build a domain reputation, provide a well known and trusted IP space to send from, and be certain that emails pass through our system instantly to make their way to your user’s inboxes. Sending only transactional messages gives us higher engagement rates which the ISPs like to see. This reduces the chance of a large influx of questionable messages that result in throttling, which helps us design Postmark around sending transactional email from your applications. As a product owner, I know that we could increase revenue instantly by offering bulk email, but our focus has been and always will be quality over quantity. 

So for now, IP addresses still matter, but as time marches on, we’re increasingly moving towards a world where reputation is tied more to your domain than the IP address from which it sends. It’s the right direction to go in for everyone and gives you more control over the reputation of your brand.

Chris Nagele

Chris Nagele

Love to travel with the wife and kids. Wannabe race car driver. Not so healthy obsession with Building Science.