What are the Advantages of a Shared IP Address vs. a Dedicated IP Address?

An important decision that all email marketers must consider at some point is deciding whether their messages should be sent from a dedicated IP address or a shared IP address.

In simple terms, a dedicated IP address is assigned to a single sender. It allows the sender full control of emails sent from their IP address. A shared IP address means other senders’ mailing campaigns use the same IP address.

Sending practices inform an IP’s reputation.

Because mailbox providers use IP reputation as one of the key factors in determining whether emails should be placed in subscriber inboxes, spam folders, or if the messages should be blocked, it seems logical that senders would want an exclusive IP address. The advantage of a dedicated IP is the control it provides over email deliverability.

However, there are other important factors that determine whether a dedicated or shared IP address is right for your email program.

Let’s review the differences and use cases for dedicated and shared IP addresses.

Dedicated IP addresses

Senders who use a dedicated IP address are accountable for their own IP reputation. Their emails won’t adopt or inherit problems from less reputable senders who may not adhere to best practices.

• Troubleshooting (and correcting) deliverability issues can be easier if a sender is using a dedicated IP address. Dedicated IP addresses allow senders to accurately measure, interpret and address key performance issues, like spam complaint rates, which may be harming their deliverability.
• Leveraging multiple dedicated IP addresses allows senders to segment based on message type, engagement level, etc., which provides an email program with greater flexibility. Having dedicated IP addresses assigned to different mail streams may help protect critical messages (i.e., transactional emails) from reputation issues that could be negatively impacting other mail types (i.e., promotional emails).
• Dedicated IP addresses can achieve both SPF alignment and DKIM alignment. As stricter authentication protocols become mailbox provider requirements, it’s important to consider this form of email legitimacy.

Last but certainly not least, Dedicated IP addresses are eligible for Validity Sender Certification. Certification is the industry’s most unique and powerful allowlist, providing benefits at major mailbox providers to ensure your emails get delivered to the inbox. The benefits of the program go far beyond increased inbox placement—learn more about Certification here.

Shared IP addresses

• Email volume is a critical component in both building and maintaining a strong IP reputation. Mailbox providers like Gmail and Yahoo respond favorably to senders who deploy email consistently. For low-volume senders, volume consistency and count can present an issue. Shared IP addresses allow low-volume mailers to establish and maintain a sending reputation with mailbox providers. While volume stipulations vary, several major email service providers (ESPs) note that senders who deploy fewer than 100,000 use a shared IP address.
• Not all email programs send daily promotional campaigns. Shared IP addresses are ideal for some seasonal mailers, who would not need to warm up dedicated IP addresses every year.
• Shared IP addresses are typically less expensive than dedicated IPs. As with buying any type of product or service, it comes down to what you need to run your business. Shared IP addresses would probably suit seasonal mailers and low-volume senders best.

While shared IP addresses are not eligible for Validity Sender Certification, they are eligible for Certification for Mandated Mail. Certification for Mandated Mail helps businesses send (potentially) time-sensitive and high-risk messages that are intended to inform their customers of critical, non-promotional information related to a triggering event that necessitates a material response. These essential messages inform recipients of critical events and should only be used for one-time notifications that are an exception to normal sending practices and cadences. Learn more about the benefits of Certification for Mandated Mail here.

Guiding questions

When considering whether your email program needs a dedicated or shared IP address, consider the following questions:

• Will my program be sending email consistently? Seasonal or occasional mailers might consider a shared IP address and avoid repetitive IP warming.
• What is my monthly email volume? Senders deploying more than 100,000 emails per month might consider a dedicated IP address.
• What is my budget?
• Does my ESP vet senders using shared IPs for best practice adherence?
• Do we want full control of our sending reputation, and does our email volume allow us to maintain that reputation?

Ultimately, understanding the reputation of your IP address is imperative to make the right decision. If you’re in a shared space, and dedicated IP addresses aren’t an option for you yet, ask your ESP what types of clients are sharing your IP addresses and what the vetting process is when new clients and email lists are added. The other senders from the shared IP will affect your inbox delivery for better or worse, and on a shared IP address you’re only as good as the weakest sender in the pool.

Learn more about your IP reputation at SenderScore.org.