Ask a Deliverability Expert: Should I Use a Custom IP Address?

These stories are presented thanks to Who Sponsors Stuff, which gives you and your team the tools to quickly find and reach out to relevant sponsors for your newsletter. They track 350+ newsletters, have direct contact information for 6,000+ sponsors, and keep you on the cutting edge of who’s spending money in the email advertising space. Find out how their Sales Pro product can supercharge your ad sales operation today.

Should I use a custom IP address? How many emails should I be sending a month before I consider it? And is there any chance it could actually cause a decrease in engagement?

Email marketing remains an indispensable tool for businesses and organizations to effectively connect with their target audience. Its wide reach and cost-efficiency enable companies to deliver personalized messages, promote products or services, nurture customer relationships, and drive conversions. However, successful email delivery is not just about crafting compelling content and hitting the “send” button to an engaged list. It also relies heavily on the underlying deliverability infrastructure, which includes IP addresses. 

In simple terms, an IP address is a unique numeric label assigned to every device that connects to a computer network, including the internet. It acts as a digital identification tag, enabling the transmission of data between devices. In the context of email delivery, IP addresses are linked to the sending servers employed by email service providers (ESPs) and organizations.

The role of IP addresses in email delivery is twofold. First, they determine the path the email takes from the sender’s server to the recipient’s inbox. Second, they are part of a sender’s historical reputation. The more readers engage with emails from a specific IP address, the better the reputation of that IP, which affects if emails are delivered to the inbox or not.

Now that we’re clear about what an IP address is and why it matters, let’s talk about the big issue: What IP address should you be sending from?

Most ESPs offer what’s known as a shared IP address. These are IP addresses that are in use by other customers of that ESP — they have a good reputation, and you can feel confident that your emails should be delivered if you send via those IPs. There’s nothing you need to do to get on a shared IP — you’re automatically assigned to one when you become a user of that ESP.

But not everyone wants to use a shared IP. Some senders would prefer to use a custom IP — something used exclusively by your organization.

There are absolutely benefits to using a custom IP, but also potential impact on email engagement. So let’s explore the pluses and minuses of a custom IP address so you can make an informed decision — shared IP or custom IP? — to optimize your email marketing strategy and achieve both better deliverability and engagement.

Choosing between a custom IP vs. shared IP

A custom IP address, also known as a dedicated IP address, is an exclusive numerical tag assigned to a particular sender’s email server. Unlike shared IP addresses, which are used by multiple senders simultaneously, a custom IP address is reserved solely for one sender or organization.

With a custom IP address, you have full control over its reputation and deliverability. This means that your email sending practices and reputation are not influenced by the actions of other senders sharing the same IP address. You can manage your IP address independently, implementing specific protocols and practices to optimize your email delivery.

In contrast to custom IP addresses, shared IP addresses are used by multiple senders to send their email campaigns. ESPs typically allocate shared IP addresses to a group of senders based on factors such as email volume, sender reputation, industry, and compliance with email best practices. Good senders will get matched on an IP with other good senders. This sharing of IP addresses spreads the reputation across multiple senders that should ultimately help each sender on a whole.

Shared IP addresses can be beneficial for senders with lower email volumes or those who are just starting with email marketing. The shared reputation allows new senders to leverage the collective goodwill of established senders. However, it also means that the deliverability and reputation of a shared IP address are influenced by the actions of all the senders using it. 

It’s important to understand that even though senders on shared IPs can influence each other’s reputation, inboxes care a lot more about individual senders and their best practices. They can tell between senders — they don’t automatically lump together every brand on a shared IP.

On the other hand, a custom IP address provides exclusive control and reputation management. It’s ideal for high-volume senders, businesses that can manage and monitor specific deliverability requirements, or organizations with stringent compliance policies. Custom IP addresses allow senders to establish and maintain their own sending reputation, independent of other senders.

It’s important to note that while custom IP addresses offer greater control, they also require additional responsibility. The sender must proactively manage their IP reputation using postmaster tools — relying on public sender scores or email testers isn’t enough. These senders must also adhere to email industry standards, and implement proper email authentication protocols to maintain deliverability and engagement rates. It isn’t enough to have the ESP monitor and manage the IP address; the sender must actively participate in maintaining a good sending reputation.

Factors to consider before adopting a custom IP address

Before deciding to adopt a custom IP address for your email marketing, there are several important factors to consider. First, take into account the volume and frequency of your email program. If you have a low email volume or infrequent sends, a shared IP address provided by your email service provider (ESP) may suffice. However, if your email volume is high or you plan to increase your sending frequency, a custom IP address becomes more relevant. High-volume senders can benefit from having a dedicated IP as it provides better control over deliverability and allows for a more tailored email sending strategy. 

As a general guideline, you may want to consider transitioning to a custom IP when you anticipate sending at least 200,000 emails over a period of a month. That doesn’t mean you should do it if you hit that volume — that would be the minimum you’d need to send for me to recommend that you consider a dedicated IP.

Another crucial factor is the quality of your email list and the level of engagement from your subscribers. A well-segmented list with active and engaged subscribers, low complaint and bounce rates, and a healthy engagement level will likely see positive results when using a custom IP address. However, if your list consists mainly of inactive or unengaged subscribers accumulated over the years, it’s advisable to first focus on re-engagement strategies, list cleaning, and improving the quality of your email list before considering a custom IP address.

Assessing your current sender reputation is also essential before adopting a custom IP address. Constantly monitoring your reputation through seedlisting tests, postmaster tools like Microsoft Smart Network Data Services and Google Postmaster, and domain/sub-domain DNSBL monitoring, using a tool like Domain Check from EmailConsul, can provide insights into your reputation with ISPs. If you already have a strong reputation and have been consistently following email industry best practices, transitioning to a custom IP can help you maintain and strengthen that reputation.

Additionally, it’s crucial to implement proper email authentication protocols, such as Sender Policy Framework (SPF), DomainKeys Identified Mail (DKIM), and Domain-based Message Authentication, Reporting, and Conformance (DMARC). These protocols establish your identity as a legitimate sender and increase your chances of inbox placement. Before moving to a custom IP, ensure that your infrastructure and technical setup support these authentication mechanisms.

Adopting a custom IP address requires adequate resources and technical expertise to manage and maintain it effectively. Consider whether you have the necessary resources, including server infrastructure and staff, to handle the additional responsibilities. If you don’t have in-house expertise, you may need to consider partnering with email deliverability specialists or consultants who can provide guidance and support in managing your custom IP address on top of what an ESP offers with their dedicated IPs. You want to ensure that you have someone constantly monitoring your deliverability who understands the ins and outs of your email program, and that this person is available when key email-related decisions are made.

Determining the right time to use a custom IP address

To determine if it’s the right time to use a custom IP address, you should assess your email sending habits and growth plans. Consider factors such as your current email volume, frequency of sends, and any anticipated growth in these areas.

If your email marketing efforts are consistently growing, with increasing volumes or higher sending frequencies, it may indicate that transitioning to a custom IP address is appropriate. Custom IPs provide greater control and scalability for high-volume senders, ensuring optimal deliverability and inbox placement as your email program expands.

However, it’s important to note that moving to dedicated IPs won’t fix current deliverability issues resulting from not following best practices or any previous abuse your brand may have experienced.

Monitoring your email performance metrics and deliverability rates is essential in determining the right time to switch to a custom IP address. Analyze key metrics such as open rates, click-through rates, bounce rates, spam complaints, and inbox placement rates. If you notice any declines, it’s important to analyze and be honest with yourself: Does the issue stem from deliverability-related issues associated with shared IPs, or is it something else? Email marketing software providers often have teams of specialists dedicated to maintaining the reputation of their IPs, keeping bad actors away, and fostering relationships with both inbox providers and blocklists. If you’re experiencing deliverability issues, don’t jump to conclusions and blame your ESP for the decline. Often, the issue isn’t the ESP — it’s you and your sending practices, and you may need to adapt to rebuild your reputation. 

Potential drawbacks and challenges to using a custom IP address

When transitioning to a custom IP address, one of the challenges is the initial warming-up process and reputation building. Unlike a shared IP, a new IP address lacks a sending history and reputation, which can initially impact deliverability rates. ISPs and email filters may view emails from the new IP with caution, potentially routing them to spam folders or blocking them altogether, even if your sender domains and subdomains have a historically strong reputation.

To overcome this challenge, it’s crucial to follow a gradual warming-up process. Begin by sending emails to a small subset of your most engaged and active subscribers — sometimes, this will be as small as a few hundred emails at the start, starting with your most-engaged subscribers. Gradually increase your sending volume and expand the recipient list over time — it might take weeks or months to fully migrate your audience to the new IP. This approach helps build a positive sending reputation and establishes trust with ISPs and email inbox providers. It’s important to remember that simply increasing volume slowly isn’t enough; you also need to strive for high engagement, too.

And I’ll say this again: During the transition to a custom IP address, there is a risk of potential deliverability issues. ISPs and email filters may temporarily flag emails from the new IP as suspicious or treat them as unfamiliar senders, leading to a temporary decrease in deliverability rates.

To mitigate these issues, it’s important to inform your subscribers about the IP transition in advance. Encourage them to whitelist your new IP address or add it to their contacts to ensure smooth inbox delivery. Additionally, closely monitor email performance metrics, engagement rates, and feedback loops during the transition phase to promptly identify and address any deliverability issues.

Proper planning, implementation, and monitoring can help mitigate potential drawbacks and challenges associated with using a custom IP address. By actively managing your IP reputation, following best practices, and staying responsive to deliverability issues, you can maximize the benefits of a dedicated IP while minimizing any negative impacts.

Using a custom IP address means taking on increased responsibility for maintaining its reputation. Unlike shared IP addresses, where reputation is influenced by multiple senders and managed by a team of dedicated specialists, with a dedicated IP, you bear sole responsibility for your sending practices, reputation, and correct infrastructure setup. Make sure you monitor your metrics closely, especially during the warm-up process. Failing to manage your IP reputation effectively can result in decreased deliverability rates and email engagement.

Strategies for successful custom IP address implementation

Deciding whether to use a custom IP address is a significant decision that should be based on your individual needs and goals. While custom IPs offer control, improved deliverability, and reputation management, they also require careful planning, technical expertise, and ongoing monitoring.

If you’re going to switch to a custom IP, think through a few factors first:

• Make sure you’re sending a high volume of emails — at least 200,000 emails sent per month. The more emails you send, the more valuable a custom IP might be for your org.
• Make sure you have the technical capacity — both the staff and knowledge — to implement and monitor your dedicated IP. If you don’t have that within your org, you may want to hire an outside consultant or agency to help you with the transition.
• Make sure you’re putting together a warm-up process for the new IP, and have the staff to implement that process.
• Make sure you’ve gone through previous authentication steps, including setting up SPF, DKIM, and DMARC.
• Make sure you’ve cleaned your email list and have a process for future list cleaning.
• Make sure you’re thinking long-term. Remember, dedicated IPs don’t fix deliverability issues if they stem from bad or outdated email practices — the responsibility falls to you to implement best practices.

By following these strategies for successful custom IP address implementation, you can maximize the benefits of using a dedicated IP. It enables you to establish a strong sending reputation, optimize deliverability rates, and enhance engagement with your email audience.

Thanks to our sponsor

The stories you’re reading on inboxcollective.com are made possible thanks to the generous support of our fall sponsor, Who Sponsors Stuff, which gives you and your team the tools to quickly find and reach out to relevant sponsors for your newsletter. They track 350+ newsletters, have direct contact information for 6,000+ sponsors, and keep you on the cutting edge of who’s spending money in the email advertising space. Find out how their Sales Pro product can supercharge your ad sales operation today.