Shared vs. Dedicated Sender IP

How to Determine the Best Option for Your Brand or Business.

Email Marketing Reality in 2024: If you ask email marketers whether they’re sending from a shared or a dedicated sender IP, it's not unusual for the team to need a quick check-in with IT or their ESP. Often, they don’t know. I mention this not to place blame or highlight weaknesses but to raise awareness about a crucial topic.

We email marketers, and I absolutely count myself among this group, often have a high focus on what we’re sending, the strategies we apply, how the emails we send look, and how we can tap into the conversion potential our database holds.

However, we tend to lose focus on what’s “beneath the hood,” or in our case, behind the software interface. And while Google, thank you very much for that, reminded us at the beginning of the year that domain authentication is a thing and that they’re going to put their foot down now - it’s only one component of a very complex infrastructure.

Another critical piece is the Sender IP, which we’ll delve into more closely today.?

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Step 1: Understand What a Sender IP Is

We’re not aiming for an in-depth technical definition here. Mailmodo has managed to break this down in a way that everyone can easily understand:

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“Sender IP address is the IP address of the device used to send your emails. It differs from a personal IP address in:

Personal IP address: The IP address of the device you're using your ESP from.

Sender IP address: The IP address of the device or server your ESP uses to send your emails.”

Step 2: Understand Why This Is Important

You have a reputation. Not only as a brand, of course, but as a sender of emails. Inbox Providers such as Gmail, GMX and Web.de have what we might call a "memory." They form an opinion about you based on how users engaged or did not engage with emails from your domains, your sender IPs, and many other factors.

Sending emails from a Sender IP that has a bad reputation due to, for example, spam complaints or low engagement can actively hurt your deliverability. In the worst case, the Sender IP might even be blacklisted, which could result in your email being pushed into SPAM or being rejected completely.

You don’t want to put all that effort into beautifully crafted emails, only to have them rejected due to a factor you can, in some or most cases, actively control.

Step 3: Review Your Options & Make a Qualified Decision

Most ESP systems categorize Sender IPs into one of two categories. Depending on your database size and sending behavior, you can choose to utilize:

Working off a "Shared Sender IP" means you're not the only entity sending from that specific IP; you're sharing it with a number of other brands.

Using a "Dedicated Sender IP" means you're the only one using the IP to send emails to your recipients.

Making a decision between the two might not be so straightforward. Both options have their benefits and issues that you need to be aware of:

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Working with a “Shared Sender IP”

• Especially smaller senders benefit from using "Shared Sender IPs". It takes a certain sending volume and consistency from an IP to build up a positive reputation. Most smaller senders, sending only a few thousand emails per month, can't manage this on their own. Combining their sending volume with that of other brands can be advantageous.
• For newcomers in email marketing, using a "Shared Sender IP" can provide an easier start. Having no sending history and needing to build up a reputation, starting off on an IP with an already good reputation can be highly beneficial.
• It's more cost-effective, which is self-explanatory.

BUT:

• You're sharing a Sender IP with brands you know nothing about in terms of their sending behavior. This means if they send emails that damage the IP's reputation, your emails on that IP are also affected, and there’s nothing you can do about it.
• The lack of control over what other brands do on your shared IP can lead to heavy fluctuations in sending volume, impacting deliverability.
• The lack of insight and options for troubleshooting if issues arise can be problematic. You’re completely dependent on the ESP and the IPs they assign you to.

Sounds quite dramatic, doesn’t it? So, what’s your real alternative? Simply put:

Working with a “Dedicated Sender IP.”

• You’re fully in control. You’re the only one using your Sender IP, allowing you to manage your deliverability by adapting your sender behavior based on the feedback you receive. No external actions will interfere with your reputation development.
• If an issue arises, it’s easier to trace the cause back to specific sender behaviors or even specific campaign contents. This enables continuous improvement in how you build emails and communicate with your recipients.

While this sounds like the perfect solution, remember, “with great power comes great responsibility.”

• Being the sole sender on your Sender IP, you need to manage all aspects of warming up the IP—meaning the initial build of your reputation and, more importantly, the maintenance of that reputation. This involves constant proactive effort and a high level of control over sending volume, campaigns, performance, and more.
• Sending a low volume of emails might result in an insufficient or decreasing reputation for your domain, thereby impacting your deliverability.
• You’re really on your own in most cases. With sole responsibility for the Sender IP, support from your ESP system might be significantly reduced.
• Don’t forget, you’ll likely have to pay an additional license fee for the Sender IP, which can be quite an investment and strain on your budget.

For these reasons, a dedicated sender domain is often recommended for mature teams and high sending volumes. The recommended thresholds vary from source to source. HubSpot mentions 100,000 emails per week as an example, while ESPs like Klaviyo only share the requirements to qualify for a dedicated IP upon request.

So, the decision really comes down to this:

Do you believe your email volume is high enough and your email marketing team mature enough to handle the additional effort and reap the benefits?

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Step 4: Monitor Your Deliverability AKA Make Sure You Made the Right Choice

There are various tools in the market, both paid and free, that provide information about your reputation as a sender, on both IP and domain levels. While the insights are sometimes not fully reliable, especially if your Shared IP is changing between campaigns, they help maintain an overview and spot issues early across all parameters that might impact your deliverability. On a Dedicated Sender IP, monitoring during the warm-up phase and afterward is an absolute must.

Without claiming completeness, here are a few tools you might find interesting:

• Sender Score
• Google Postmaster Tools
• Microsoft SNDS
• MX Toolbox

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Let’s Proactively Enable Our Email Marketing Teams

For all of you who would love to have a heated discussion with me about the potentials and challenges of building knowledge on deliverability-focused marketing teams - I’ll be speaking about exactly this topic at the CSA Email Summit in Cologne, from April 22 – 24, 2024. I would love to see you there!

Your email geek,

Janine