A dedicated IP vs a shared IP for sending email: How do you choose?

Say you're sending an email to a friend or a client. Your requirement is that the email reaches the recipient's inbox. If delivery is important for a simple email to your friend, imagine how it is for transactional emails that are sent from your business. No matter what the intention of the email is, the primary goal is for it to be delivered to the recipient's inbox on time.

This delivery largely depends on your sender reputation, and the internet protocol (IP) reputation is a huge part of how your sender reputation is calculated. In this article, we'll see what an IP address is, how it affects your email deliverability, the different types of IPs, and which one is ideal for your email sending.

What is an IP address? 

In the physical world, your home or office address is usually how people locate you. Say they have something to deliver or they just want to connect with you; they'll use your address to locate you.

An IP address is essentially your address on the internet. It’s a unique identifier that denotes a particular location on the web. An IP address is multiple numbers separated by periods, where each number is in the 0 to 255 range. For example, 112.3.43.233, 232.22.4.54, 54.2.34.023, etc.

These IP addresses are assigned by your internet service provider (ISP) to your internet connection or domain. The domain is mapped to the IP address using a domain name system (DNS). Imaging having to remember a string of numbers for every website you might want to visit. Instead, thanks to DNS mapping of IPs to domains, you simply need to remember a domain name, like www.zoho.com.

Today, there are two IP protocols—IPv4 and IPv6. IPv4 is the first version of IP protocols. It uses a 32-bit address like the ones mentioned above (112.3.43.233). As internet adoption grew, it created a problem of running out of IP addresses. As a solution to this, IPv6 came into place. This protocol uses 128-bit addresses that can accommodate with scaling IP address assignment. An example of a IPv6 address would be: 2001:db8:85a3:0:0:8a2e:370:7334.

How does an IP address and its reputation affect your email deliverability? 

We started this article talking about the primary goal of sending email—ensuring that the email lands in the recipient's inbox. It cannot end up in the spam pile or be delivered hours after it was sent. The sender reputation of the email sender (in this case, you) is one of the deciding factors in your email's deliverability. Sender reputation is a combination of multiple factors, and one of the key factors is the IP reputation.

An IP reputation is decided by past email sending activities and behaviors. Based on the reputation, receiving email service providers (ESPs) tend to make an assumption upfront about the quality and intention of your email. To put it simply, when an ESP receives your email, they do a quick background check to see how emails from your IP have been treated previously. If too many were considered spam or otherwise unnecessary, ESPs could jump to the conclusion that the email they've received is of low quality and importance, leading to them being blocked from the recipient's inbox.

Ensuring that your email sending IP has a great reputation is non-negotiable if you want your emails to be delivered in your recipient's inbox instead of being sent to the spam folder or simply being rejected.

Types of IP addresses, and how they differ 

There are two types of IP addresses you can choose from for your email sending needs: A shared IP address and a dedicated IP address.

The difference between the two only lies in who sends emails from the IPs. In the case of shared IP addresses, multiple users will be using the IP to send their emails. When it comes to dedicated IP addresses, you’re assigned a unique IP address that is only used by you to send your emails.

Each of these types come with their own pros and cons. It's not a case of one size fits all. We now know that IP reputation is key for good email deliverability, so picking the right type of IP address for your email sending needs is important. Let's take a quick look at what each type has to offer.

Shared IPs 

Shared IPs, as the name suggests, are IP addresses used by a pool of users for sending email. Let's start by looking at the pros of using a shared IP address.

You can hit the road running 

If you’re a new sender or a small-volume sender, shared IPs are a way to immediately start sending emails with good deliverability. In spite of a lack of email sending history from you, a shared IP will allow you to piggyback off the reputation that the other senders in the IP have built over time. The necessity of and time spent on warming up the IP for email sending is virtually none.

Reap the benefits of good sending practices 

In a shared IP, your IP reputation is linked with the email sending practices of other users in the same pool, but more often than not this is beneficial for you. Most reputed email providers vet their users before allowing them to use shared IPs. Sharing an IP address with these good senders can help boost your IP reputation and, in turn, your sender reputation. Finding a good email provider that vets its users is key to getting shared IPs to work for you.

Shared responsibility means less responsibility 

Consistency in email volume and frequency is essential in maintaining a good IP reputation. With shared IPs, the responsibility of maintaining the IP falls on a group of users instead of just you. With a pool of users using the shared IP, frequency and volume are usually taken care of.

Mistakes usually aren’t catastrophic 

It’s a simple case of the good practices of other users camouflaging your mistake. Consistently bad emails, volumes, or frequency will be punished but, once in a while, mistakes are penalized less severely when using a shared IP. You can recover from these one-off incidents more quickly by using the other senders' reputation.

It’s less expensive, of course 

As you would expect, shared IPs are more economical by a huge margin. With maintenance and the costs of running the IP shared among a pool of users, each user is charged a small and reasonable amount.

While this might not be a factor for everyone, for new senders or low-volume senders shared IPs might be the best option that also doesn’t burn a hole in your pocket.

Now for the downside of shared IPs. 

Bad senders impact your reputation 

This is essentially the only downside of a shared IP. If your pool comprises bad senders who don’t follow good practices or are downright spammers, then your sender reputation takes a hit simply as a consequence of sharing an IP with them. While it’s inconvenient, in most cases picking a good email provider who weeds out bad senders can help avoid this complication.

Dedicated IPs

Now let's take a look at what dedicated IPs have to offer and where they fall short. Let's start with the pros:

Keep complete control over your IP reputation 

A dedicated IP is assigned to you, and only you can send emails from the IP. This gives you full control over the IP and its reputation. Unlike shared IPs, the bad practices of other senders will not impact your sender reputation or email deliverability.

Zero in on deliverability issues 

In a shared IP with multiple senders, getting to the root of the IP problem can be difficult. If you're using a dedicated IP and come across IP issues, it’s much easier to lock down what the issue is and troubleshoot it.

A chance of being whitelisted 

Providers are usually skeptical of whitelisting shared IPs, but dedicated IPs do have a shot at being whitelisted. With the authority of being the only sender using a dedicated IP, you can request your email sending IP to be whitelisted by certain ESPs. Being whitelisted will guarantee delivery with these ESPs and help boost sender reputation among other ESPs.

Now for the cons of dedicated IPs:

Missing out on having fellow good senders 

Being a team player can help when it comes to IP reputation. While there is a risk of bad senders, using a dedicated IP would mean that you lose out on the opportunity to use the good email practices of fellow senders to boost your own reputation.

With great power comes great responsibility 

Imagine you live alone in a big house. It might sound like fun, but when it’s cleaning time, you'll miss having roommates. Similarly, while you get to enjoy full control over the IP reputation while using a dedicated IP, the full burden of maintaining the IP falls on you. You have to be extremely careful to maintain a consistent volume and frequency along with ensuring that you send good emails.

Mistakes can be expensive 

The margin for error with dedicated IPs is very small. When you’re the sole sender in the IP, there's nowhere to hide. Dropping the ball even once can lead to serious damage to your IP reputation. If that isn't enough, recovering from the mistake is an uphill battle with no help from fellow senders to boost your reputation.

Which one should you choose? 

There’s no one right answer to this question. The right type of IP address for you is decided by multiple factors like sending volume, frequency, existing reputation, budget, and much more.

In general, a dedicated IP is often promoted as the magic potion for email deliverability by many providers looking to monetize it. In reality, a dedicated IP is required and beneficial only to a very small percentage of senders. In fact, if you’re a low-volume sender or inconsistent sender, using a dedicated IP could do more harm than good. At ZeptoMail, deliverability isn't an add on. It’s guaranteed whether you use a shared IP or dedicated IP.

If you've read this article till this point, you already have an idea of which is the best approach for you. Here's the bottom line:

Choose a shared IP if:

• You’re a new sender who is just starting out.

• You’re a low-volume or inconsistent sender.

• You have a small budget to spend on an email sending IP.

Choose a dedicated IP if:

• You’re facing deliverability issues with shared IPs from reputed providers.

• You’re a high-volume sender with consistent frequency.

• You’re confident in your email practices.

• You have a proven reputation and can afford to build on it with a dedicated IP.

While choosing the right IP address goes deeper than following a simple checklist, here are some quick pointers that will help in your decision-making. Whichever IP type has more instances of “Yes” under it, is likely to be the choice more suitable to you.

Wrapping up 

Picking the right type of IP address is critical. Often a combination of multiple factors, 99% of the time using a shared IP is the best way to build your reputation. ZeptoMail offers well-maintained shared IPs that are shared among thoroughly vetted users. But if you fall in the 1%, we also provide dedicated IPs for users that meet the criteria in email sending volume, frequency, and requirements.