Is a shared IP address always better for low-volume email sending?

For low-volume senders, typically under 50,000 to 100,000 emails per month, a shared IP is generally more suitable. Your sending volume on a dedicated IP might be too low to maintain a consistent, positive reputation with mailbox providers, potentially leading to deliverability issues. Shared IPs benefit from the combined volume of many senders, helping to keep the IP warm and reputable. You can learn more about if a dedicated IP is suitable for low volume here.

Can bad sending by others on a shared IP affect my email deliverability?

Yes, it can. While shared IPs are managed by your ESP, if other senders on the same IP engage in problematic sending practices (e.g., sending spam, high bounce rates), it can negatively impact the shared IP's reputation, which in turn can affect your deliverability. This is why choosing a reputable ESP with strong anti-spam policies is important when using shared IPs. Also, even on a shared IP, your domain's reputation is still key. If your sending practices are poor, your domain can still be penalized, irrespective of the IP.

What is IP warming, and is it necessary for shared IPs?

IP warming is the process of gradually increasing the volume of emails sent from a new IP address over time. This helps mailbox providers recognize your IP as a legitimate sender and build a positive reputation. It's crucial for dedicated IPs because they start with no sending history. Shared IPs, by contrast, are usually pre-warmed and continuously managed by the ESP, so individual senders typically don't need to perform warming for them. Learn more about when a dedicated IP is needed .

Does a dedicated IP guarantee better deliverability than a shared IP?

While a dedicated IP gives you more control, it doesn't guarantee perfect deliverability. Your content quality, list hygiene, recipient engagement, and compliance with email best practices still play a huge role. A dedicated IP simply removes the variable of other senders impacting your reputation. If your own sending habits are poor, even a dedicated IP will struggle. However, for high-volume senders , it provides the necessary infrastructure to scale deliverability responsibly.

When should I use a shared IP address over a dedicated IP address for email sending? - Sender reputation - Email deliverability - Knowledge base

Choosing the right IP address for your email sending strategy is a pivotal decision that directly impacts your deliverability. It's not a one-size-fits-all solution; the optimal choice between a shared IP and a dedicated IP depends heavily on your specific sending volume, consistency, and overall email program maturity.

Many senders initially default to a shared IP because it seems simpler, while others might jump to a dedicated IP assuming it automatically grants better inbox placement. The truth is more nuanced.

Understanding the core differences and the implications for your sender reputation is crucial for making an informed decision that supports your long-term email success.

Understanding email IP addresses

An IP (Internet Protocol) address is a unique numerical label assigned to every device connected to a computer network that uses the Internet Protocol for communication. In the context of email, your IP address is like the return address on a letter, signaling to recipient servers where the email originated.

Your sending IP's reputation plays a significant role in how mailbox providers like Gmail, Outlook, and Yahoo perceive your emails. A strong IP reputation means your emails are more likely to reach the inbox, while a poor one can lead to messages being filtered to spam or rejected entirely.

Shared IP addresses

A shared IP address is exactly what it sounds like: an IP address used by multiple senders. When you send emails from a shared IP, your deliverability is influenced by the sending practices of everyone else using that same IP. This can be both a benefit and a risk.

Shared IP addresses are typically managed and warmed up by your Email Service Provider (ESP). They handle the heavy lifting of maintaining a good reputation for the IP pool, which can be advantageous for new or low-volume senders. However, if a co-sender misbehaves and gets the IP blocklisted (or blacklisted), your emails could be affected, even if your practices are pristine.

Dedicated IP addresses

A dedicated IP address is an IP address exclusively used by you for sending emails. This means your entire sending reputation, good or bad, rests solely on your own sending practices. You have full control, but also full responsibility.

With a dedicated IP, you are responsible for warming up the IP to build a positive sending history. This involves gradually increasing your sending volume over time. The upside is that you're insulated from the poor sending habits of others. The downside is that any missteps you make can quickly damage your own reputation, making it harder for your emails to reach the inbox.

The advantages of using a shared IP

For many senders, especially those just starting out or with irregular sending patterns, a shared IP address is often the superior choice. ESPs (Email Service Providers) manage vast pools of shared IPs, which means they come pre-warmed and are constantly monitored to ensure a good collective reputation.

If you send a low volume of emails, say less than 50,000 per month, or your sending is inconsistent, a shared IP can actually provide better deliverability. This is because your individual sending volume might not be enough to sustain a good reputation on a dedicated IP, leading to inconsistent performance and potential filtering issues. On a shared IP, your low volume blends in with the higher volume of other senders, benefiting from the overall good reputation of the pool.

Ideal scenarios for shared IPs

Low volume: If you send under 50,000 to 100,000 emails per month, a shared IP is generally recommended to leverage the collective reputation and warming efforts of the ESP.
Inconsistent sending: For irregular senders, like quarterly newsletters or occasional announcements, a dedicated IP's reputation could decay between sends. Shared IPs maintain their reputation through continuous, combined activity.
New senders: A shared IP provides a ready-to-use, warmed IP, bypassing the need for a lengthy IP warming process. This allows you to start sending immediately without worrying about building reputation from scratch.
Cost-effectiveness: Shared IPs are often included as part of standard ESP plans, making them a more economical choice compared to the added cost of a dedicated IP.

When a dedicated IP address is essential

While shared IPs are excellent for many, a dedicated IP address becomes crucial when you reach a certain scale and consistency in your email sending. High-volume senders, typically those sending over 100,000 emails per month consistently, often find that a dedicated IP gives them more control over their deliverability fate. This control is vital for maintaining consistent inbox placement for critical communications.

The primary benefit of a dedicated IP is isolation. Your reputation is yours alone, meaning you won't be impacted by the negative sending habits of others. This is particularly important for transactional emails (e.g., password resets, order confirmations) where timely and reliable delivery is paramount. However, with this control comes the responsibility of meticulous IP warming and consistent monitoring of your IP reputation, including watching out for any blocklist (or blacklist) placements.

Aspect	Shared IP	Dedicated IP
Email volume	Low or irregular sending volumes (e.g., <50k-100k emails/month).	High, consistent sending volumes (e.g., >100k emails/month), as discussed on AWS's documentation.
Reputation control	Shared with other senders, managed by ESP, susceptible to co-sender's actions.	Full control and responsibility over your IP reputation.
IP warming	Generally unnecessary, as IPs are pre-warmed by the ESP.	Essential and requires a strategic, gradual increase in sending volume.
Cost	Often included in standard ESP packages.	Typically an additional fee, reflecting the exclusivity and control.

Key factors to consider for your IP choice

Beyond volume and consistency, the type of emails you send and your overall email strategy should heavily influence your IP decision. For instance, if you send highly sensitive or time-critical transactional emails, a dedicated IP might be worth the investment for the added reliability and control over your sending environment.

Conversely, trying to leverage a shared IP for high-risk sending, or using different IPs for different content types from the same domain, can be counterproductive. Mailbox providers assess reputation at both the IP and domain level. Sending emails perceived as lower quality from a shared IP to protect a dedicated IP can still negatively impact your domain's overall reputation, regardless of which IP is used.

Important considerations

Content consistency: Your email content and recipient engagement should be consistent, regardless of IP type. Shifting problematic sends to a shared IP to preserve dedicated IP reputation is a risky practice that can harm your domain.
Domain reputation: Your domain's reputation is often more critical than your IP's. Poor sending practices, even on a shared IP, can still negatively affect your domain's standing.
ESP quality: The quality of your ESP's shared IP pool matters. A well-managed pool with strict anti-spam policies can offer surprisingly good deliverability for many senders.

Views from the trenches

Best practices

Maintain consistent sending volumes and positive engagement metrics.

Segment your audience effectively to send relevant content.

Regularly clean your email lists to remove inactive or invalid addresses.

Common pitfalls

Switching between dedicated and shared IPs for different content types to avoid reputation hits on your main domain.

Failing to warm up a new dedicated IP address gradually.

Ignoring sender reputation metrics when using a dedicated IP.

Expert tips

Focus on domain reputation first, as it often has a greater impact.

Don't try to game the system by sending low-quality content on a different IP.

Regularly monitor your deliverability and IP health.

Expert view

Expert from Email Geeks says that trying to shift recourse and reputation issues from a dedicated IP for a less than ideal send is a risky strategy. Their main domain will likely take a reputation hit because of their email activities elsewhere.

2021-03-24 - Email Geeks

Expert view

Expert from Email Geeks says that attempting to send questionable content from a shared IP to protect a dedicated IP's reputation is effectively a spamming strategy and should be avoided.

2021-03-25 - Email Geeks

Making the right IP choice for your email program

The choice between a shared IP and a dedicated IP is less about one being inherently better than the other and more about aligning with your sending profile. For new, low-volume, or inconsistent senders, a shared IP offers a reliable, low-maintenance entry point into email marketing.

As your email program matures and your volume grows to a consistent high level, a dedicated IP provides the control necessary to fine-tune your deliverability and build a robust, independent sender reputation. Always prioritize good sending practices, regardless of your IP choice, as this fundamentally underpins your email success.