What is a dedicated IP address?

A dedicated IP address is an exclusive IP address assigned to a single sender or organization for sending emails. This means your sender reputation is tied solely to your sending practices, unlike a shared IP where it's influenced by multiple senders.

Why is IP warming important for dedicated IPs?

IP warming is the process of gradually increasing the volume of emails sent from a new dedicated IP address. This helps ISPs recognize your sending patterns as legitimate and build a positive reputation, preventing your emails from being flagged as spam.

Can I use a dedicated IP for low email volume?

A dedicated IP is generally not recommended for very low email volumes (e.g., less than 50,000-100,000 emails per month). Without sufficient, consistent volume, it's challenging to build and maintain a strong reputation for the IP, which can negatively impact deliverability. Shared IPs are often more suitable for low-volume senders.

How does sending consistency affect my dedicated IP reputation?

Yes, consistent sending is crucial for dedicated IP reputation. ISPs prefer steady email streams. Inconsistent volumes, sudden spikes, or long periods of inactivity can make your IP appear suspicious, potentially leading to increased filtering or blocklisting (blacklisting).

When should I consider adding more dedicated IPs?

You should consider adding more dedicated IPs when your volume significantly increases (e.g., consistently sending millions of emails monthly or daily), when you need to segment different email streams (like transactional vs. marketing), or to distribute sending load for enhanced throughput and redundancy.

How many dedicated IPs are needed for sending email volume? - Sender reputation - Email deliverability - Knowledge base

One of the most common questions in email deliverability is how many dedicated IP addresses you truly need for your sending volume. It's a nuanced topic, and the answer isn't a simple number. While some providers offer general guidelines, the ideal number of dedicated IPs depends on various factors beyond just the sheer volume of emails you send.

The goal with any IP strategy, whether shared or dedicated, is to maintain a strong sender reputation. This reputation directly influences whether your emails land in the inbox or are diverted to the spam folder, or even rejected outright. When you use a dedicated IP, you have full control over that reputation, meaning your sending practices, good or bad, directly impact your deliverability. This is why getting the number of IPs right for your volume is critical.

For senders with very high volumes, managing multiple dedicated IPs can be a strategic move to optimize throughput and mitigate risk. But for others, an excessive number of IPs for a given volume can be inefficient and even counterproductive to building a robust sender history. Let's delve into the details to understand how to make the best decision for your email program.

The foundation of dedicated IP addresses

A dedicated IP address is an internet protocol address exclusively assigned to you for sending emails. Unlike shared IPs, where your sending reputation is influenced by other senders using the same IP, a dedicated IP's reputation is solely yours to build and maintain. This gives you greater control and visibility over your email deliverability outcomes.

However, this control comes with responsibility. A dedicated IP requires a consistent and sufficient sending volume to establish and maintain a positive sender reputation with internet service providers (ISPs). If your volume is too low or inconsistent, ISPs have less data to evaluate your sending behavior, which can lead to slower warm-up times, slower delivery, or increased filtering to the spam folder.

The core benefit is that your sending practices directly reflect on your IP's reputation. If you maintain a clean mailing list, send relevant content, and see high engagement, your dedicated IP's reputation will thrive. Conversely, issues like high bounce rates, spam complaints, or sending to a blocklist (or blacklist) can quickly damage your IP's standing, impacting all your subsequent sends.

Volume guidelines from industry providers

Different email service providers (ESPs) and industry experts offer varying recommendations for the minimum and maximum email volume per dedicated IP. These guidelines are often based on their internal systems, network capacity, and historical data regarding how ISPs react to certain sending patterns.

Common thresholds for needing a dedicated IP generally start around 50,000 to 100,000 emails per month. Some providers suggest a dedicated IP for every 2 million emails in your plan size or recommend one IP for every 50,000 to 100,000 emails sent in a single campaign. For very high volumes, you might see recommendations for multiple IPs, such as two dedicated IPs for 250,000 messages per month, or even one dedicated IP per 2.5 million emails per month.

Provider/Source	Recommended Volume per Dedicated IP
Amazon SES	Several hundred emails within 24 hours to cultivate reputation for each ISP , or max 10,000 sending identities.
Salesforce Marketing Cloud	Over 100,000 emails/month; beyond 250,000/month, multiple IPs.
SendGrid	250,000 messages/month minimum for two IPs.
Mailjet	Over 100,000 emails/month; at least 3,000 messages daily.
Postmark	At least 300,000 messages/month.

A crucial aspect of dedicated IP management is the IP warming process. A new IP starts with no reputation, so you must gradually increase your sending volume over time. This slow ramp-up helps ISPs recognize your sending patterns as legitimate, preventing your emails from being flagged as spam. Without sufficient volume, it's hard to properly warm an IP and build a reliable sending history. Generally, you need to send at least 50,000 to 100,000 emails per month to keep a dedicated IP warm and maintain its reputation.

For some businesses, an email volume of less than 50,000 emails per month might not justify the use of a dedicated IP. In such cases, a shared IP environment could be more suitable, as the ESP handles the overall IP reputation management. You can explore more on what email volume justifies using a dedicated IP for more insights.

Beyond volume: other critical factors

While volume is a major consideration, it's not the only factor in determining the number of dedicated IPs you need. Several other elements can influence your IP allocation strategy and overall deliverability.

Email stream segmentation

It's often beneficial to separate different types of email traffic onto distinct IP addresses or subdomains. For example, transactional emails (like order confirmations or password resets) typically have higher engagement and lower complaint rates than marketing emails. Mixing these streams on a single IP means that a negative reputation from your marketing campaigns could impact the deliverability of your critical transactional messages. Dividing these streams allows you to isolate reputation risks.

Sending consistency and cadence

ISPs prefer consistent sending patterns. Sudden spikes or drops in volume can trigger spam filters, regardless of your overall reputation. If your email volume fluctuates wildly, a single dedicated IP might struggle to maintain a stable reputation. Inconsistent high-volume sending might also necessitate multiple IPs for load balancing and to prevent ISPs from closing connections due to perceived abuse.

Consistent sending is key

Maintaining a steady email sending cadence is vital for your dedicated IP's health. ISPs monitor sending behavior closely, and unpredictable volumes can signal suspicious activity, leading to inbox placement issues. Gradually increase or decrease volume to allow for a smooth transition and consistent reputation building.

Audience quality and engagement

Even with optimal IP allocation, poor list hygiene or low engagement can severely harm your sender reputation. High bounce rates, spam complaints, and sending to spam traps are red flags that can lead to your IP being added to a blocklist (or blacklist). Regularly cleaning your list and focusing on engaged subscribers is paramount. You can learn more in our guide on how email blacklists actually work.

When more IPs become necessary

While a single dedicated IP can handle substantial volume, there are situations where adding more IPs becomes not just beneficial, but necessary. This typically occurs when you're dealing with extremely high daily volumes, have diverse email streams with different risk profiles, or need to enhance throughput and deliverability resilience.

Single IP strategy

Control: Full, centralized control over your sender reputation.
Warm-up: Easier to manage the warm-up process for one IP.
Volume: Suitable for volumes up to several million emails per month, depending on quality.
Risk: Higher risk if reputation drops, as all emails are affected.

Multiple IP strategy

Control: Allows for segmenting reputation based on email stream or risk.
Warm-up: More complex, as each IP needs its own warm-up period.
Volume: Essential for volumes exceeding 5-10 million per month to distribute load.
Risk: Mitigates risk, as one IP's poor reputation won't affect others.

For example, if you send 2.5 million emails daily, you might choose to distribute this across 4 dedicated IPs to ensure smooth delivery and prevent ISPs from load shedding by closing connections. If you're a major social media company sending tens of millions of emails daily across multiple streams, a single IP simply won't suffice due to network engineering and load balancing requirements. This is where multiple IP addresses become necessary for volume.

Ultimately, the decision to add more dedicated IPs should be based on a holistic view of your sending program. This includes your specific sending volumes, the nature of your email content (transactional vs. marketing), your sending frequency, recipient engagement, and your team's ability to manage multiple IPs and their respective reputations. Continuously monitoring your blocklist (blacklist) status and overall deliverability metrics will provide the best indicators for when it’s time to scale your IP infrastructure. You can find more information on when email senders need more dedicated IPs.

Views from the trenches

Best practices

Maintain a consistent sending volume and schedule to build a stable IP reputation with ISPs.

Segment your email streams (transactional, marketing) onto different IPs or subdomains to isolate reputation risks.

Regularly clean your email lists to minimize bounces and spam complaints, regardless of IP count.

For extremely high volumes (millions daily), use multiple IPs for load balancing and to avoid ISP throttling.

Monitor your deliverability metrics and blocklist status closely to make informed decisions about IP allocation.

Common pitfalls

Using too many dedicated IPs for low volume, which makes it harder to warm and maintain reputation for each.

Inconsistent sending patterns on dedicated IPs, leading to slower warm-up and filtering issues.

Mixing high-risk email streams with critical transactional emails on the same IP.

Ignoring audience engagement and list quality, which can damage any IP's reputation.

Not having a plan for scaling IP infrastructure as email volume grows over time.

Expert tips

My current threshold for dedicated IPs is 1 million emails per day. As long as a client maintains a decent reputation, it works.

One client successfully sent 20 million emails per day per IP, but we worked to get them closer to 2 million IPs for better load balancing.

For very large senders (like big social media companies), multiple IPs are crucial for network engineering and avoiding ISP connection closures.

The specific resources a client has—like DevOps, sysadmin, and delivery teams—should influence IP recommendations.

Using a shared IP pool differs significantly from a dedicated snowshoe operation aimed at hiding bad reputation.

Expert view

Expert from Email Geeks says his current threshold for dedicated IPs is 1 million emails per day, and if the client maintains a decent reputation, it works fine.

March 13, 2022 - Email Geeks

Marketer view

Marketer from Email Geeks says they wonder why multiple IPs are needed behind a domain for more volume if it's not about dividing different mail streams.

March 13, 2022 - Email Geeks

Finding your optimal IP strategy

Determining the exact number of dedicated IPs needed for your email sending volume is a dynamic process, not a fixed rule. While general guidelines exist, such as 100,000 to 250,000 emails per month for a single dedicated IP, or up to 2 million per day for highly optimized setups, the ultimate decision depends on several interacting factors.

Effective IP allocation requires a deep understanding of your email program, including your sending cadence, the nature of your content, and the quality of your recipient list. Regular monitoring of your deliverability, engagement, and blocklist (or blacklist) status is essential to adapt your IP strategy as your volume and sending patterns evolve, ensuring your messages consistently reach the inbox.