What defines an 'active user' for IP warming purposes?

Active users are subscribers who have recently engaged with your emails by opening, clicking links, or otherwise interacting with your content. This engagement signals to mailbox providers that your emails are valued, which is crucial for building a positive sender reputation during IP warming.

What's a good initial daily sending volume for a new IP?

For a brand new IP, a common starting point is around 100-500 emails per day for each major mailbox provider (like Gmail, Yahoo, and Outlook). This low volume allows ISPs to gradually recognize your sending patterns and evaluate your reputation based on initial engagement.

How do I know if my IP warming is going well?

You should aim for consistent positive engagement metrics, such as open rates of 20% or higher and very low spam complaint rates (below 0.1%). Monitoring these metrics daily and adjusting your sending volume accordingly is key. If you see negative signals, slow down your ramp-up.

Should I segment my active users by mailbox provider during warming?

Yes, segmenting your audience by mailbox provider (e.g., Gmail, Yahoo, Outlook) is highly recommended. This allows you to manage your reputation with each provider individually and adjust your sending strategy based on their specific responses.

How many active users should be targeted for IP warming? - Sender reputation - Email deliverability - Knowledge base

When you embark on the journey of IP warming, one of the most common questions that comes up is, "How many active users should I target?" The answer isn't a single number, but rather a dynamic strategy that adapts to your unique sending profile. IP warming is essentially about building trust with mailbox providers (ISPs) like Gmail and Yahoo. It involves gradually increasing your email volume from a new or cold IP address to establish a positive sending reputation.

The key to a successful warmup is to demonstrate consistent, positive engagement from your recipients. This means starting with users who are most likely to open, click, and interact positively with your emails. If you send too many emails too soon, or to unengaged users, you risk triggering spam filters and landing on a blocklist (or blacklist), which can significantly hinder your deliverability.

I often see marketers eager to reach their full sending volume quickly, but patience is vital. A rushed warm-up can do more harm than good, leading to long-term deliverability issues. It's not just about the numbers, but the quality of engagement from those numbers.

Initial daily volumes for IP warming

When beginning your IP warming, the initial volume of active users to target is usually quite small. For a brand-new IP, a common starting point might be around 100 emails per day for each major mailbox provider.

This low volume allows ISPs to gradually recognize your sending patterns and evaluate your reputation based on the engagement signals from these highly active recipients. The goal is to send enough volume to be noticed, but not so much that you overwhelm the system and trigger automated defenses.

Defining active users is crucial. These are not just any subscribers, but those who have recently opened or clicked your emails. Typically, this means engagement within the last 30 to 90 days. Some even narrow it down to the last 7 days for the initial sends to ensure the highest possible positive response rate. The more recently they've engaged, the better. This strategy helps to establish a strong initial sender reputation.

The exact number also depends on your total list size and intended sending frequency. For instance, a very small list might not even support the typical ramp-up volumes, making IP warming for low volume senders a slightly different process compared to high-volume senders. Generally, you will increase your daily volume by 10-20% each day, depending on performance.

Day	Target Volume
Day 1	100-500
Day 2	120-600
Day 3	144-720
Day 7	~360-1800
Week 2-4	Gradual increase by 10-20% daily

The importance of segmentation

One effective strategy for IP warming involves segmenting your audience by mailbox provider. Instead of sending the same volume to all recipients, you tailor your sending based on the specific provider, such as how to target mailbox providers. For example, you might have separate segments for

Gmail,

Yahoo/AOL/Verizon,

Outlook/Hotmail/MSN/Live, and then everyone else.

This segmentation allows you to manage your sender reputation more granularly with each major provider. Some providers might be more forgiving, while others have stricter filtering rules. By segmenting, you can adjust your sending volume and strategy for each, ensuring that you don't negatively impact your reputation across the board if one provider reacts poorly.

Another consideration is to vary your segments based on recency of engagement. Begin with your most recent engagers (e.g., last 7 days), then expand to those who engaged within 30 days, then 60, and so on. This ensures a steady stream of highly engaged users during the critical early stages of warming.

Segmenting your audience

By ISP: Create separate segments for major mailbox providers like Google, Microsoft, and Yahoo/AOL/Verizon.
By engagement: Start with your most active and loyal users, then gradually move to less engaged segments as your reputation builds.
By source: If applicable, you might even consider segmenting based on how users joined your list, focusing on those with the highest proven engagement.

Monitoring and adjusting your strategy

Successful IP warming isn't just about sticking to a schedule, it's about constant monitoring and agile adjustment. You need to keep a close eye on your key deliverability metrics after each send. These metrics include open rates, click-through rates, bounce rates, and crucially, spam complaint rates. For example, a target open rate of around 20% is generally good during warming, but this can vary. If you're seeing lower engagement or higher complaints, it's a clear signal to slow down.

Mailbox providers are essentially looking for predictable, positive sending behavior. Sudden spikes in volume, high bounce rates (especially hard bounces), or an increase in spam complaints can instantly damage your nascent reputation and trigger a blocklist (or blacklist) entry. This is where the flexibility in your warming plan comes in.

If your deliverability suffers at a particular mailbox provider, or across all of them, you need to be prepared to halt your volume increases or even reduce your sending volume until you achieve a comfortable rate again. This iterative process, adjusting based on daily results, is what truly builds a solid foundation for long-term email success.

Positive signals during warming

High open rates: Consistent 20% or higher is ideal, showing recipients value your content.
Strong click rates: Indicates engagement beyond just opening, driving positive interaction.
Low bounce rates: Below 2% is excellent, demonstrating a clean and valid list.
Minimal spam complaints: Ideally below 0.1%, showing recipients expect and want your mail.

Negative signals during warming

Spike in bounces: Can indicate poor list hygiene or aggressive sending to unknown users.
Increased spam complaints: Recipients marking your emails as spam signals low relevance or unexpected mail.
Low engagement: Low open and click rates suggest your content isn't resonating or is hitting the spam folder.
Delayed delivery: Mailbox providers may intentionally slow down your sends if they are suspicious.

Factors influencing target volume

The ideal number of active users to target for IP warming isn't fixed because several factors influence the warming trajectory. Your total list size plays a significant role; a list of 100,000 active users will have a different warming plan than one with 10 million. Similarly, your sending frequency(daily versus weekly sends) impacts how quickly you can ramp up.

The engagement level of your chosen segments is paramount. Starting with the most engaged subscribers who consistently open and click helps to send strong positive signals to ISPs. This establishes a baseline of trust. As you progress, you can gradually introduce less active, but still opted-in, segments of your list.

If your primary sending is transactional emails, the warming process might be more straightforward due to higher expected engagement. For marketing emails, where engagement can be more varied, a more cautious approach is needed. Additionally, consider if you are using a shared IP versus a dedicated IP. Dedicated IPs require active warming because you are solely responsible for its reputation.

Key factors influencing warming volume

Audience size: Larger total lists allow for higher daily warming volumes once initial trust is built.
Engagement data: The more recent and consistent the engagement, the smoother the warming process.
Email type: Transactional emails generally warm faster due to their high expected engagement.
Sending frequency: Daily sends allow for faster ramp-up than weekly or monthly sends.

The path to a trusted sender

Ultimately, the question of how many active users to target isn't about a fixed number, but about adhering to best practices that build a strong sender reputation. While specific volumes vary, the underlying principles remain consistent: start small, target your most engaged recipients, monitor performance closely, and adjust as needed. This meticulous approach ensures your emails consistently reach the inbox.

Maintaining a healthy sender reputation is an ongoing effort, extending beyond the initial warming phase. Regular list hygiene, content relevance, and consistent monitoring of engagement signals will continue to be critical for long-term deliverability success. Remember, a warmed IP is a valuable asset, but it requires continuous care.

Views from the trenches

Best practices

Always start with your most engaged subscribers who have interacted recently, typically within the last 30-60 days.

Segment your audience by major mailbox providers, such as Gmail, Yahoo, and Outlook, to manage reputation separately.

Increase your sending volume gradually, often by 10-20% daily, based on positive engagement metrics.

Monitor key metrics like open rates, click-through rates, and spam complaints meticulously during the warming period.

Be prepared to slow down or even pause sending if you observe negative feedback or drops in deliverability.

Common pitfalls

Sending to too many unengaged or old contacts early in the warming process, which can quickly damage your reputation.

Rushing the warm-up by increasing volume too quickly, leading to blocks or emails landing in spam folders.

Failing to segment your audience, which prevents tailored warming strategies for different mailbox providers.

Ignoring feedback loops and bounce reports, missing critical signals that indicate issues with your sending.

Not maintaining consistent sending volume after warming, as inconsistent activity can lead to a 'cold' IP again.

Expert tips

Adjust your definition of 'active' users based on your overall list size and historical engagement data.

Consider reaching out to Outlook's postmaster team if you are warming a new IP address to inform them of your activity.

Aim for a consistent open rate, around 20% or higher, during warming as a primary indicator of healthy progress.

Prioritize transactional emails if you have them, as their naturally higher engagement aids faster warming.

Remember that IP warming is an ongoing process that extends beyond the initial ramp-up period.

Expert view

Expert from Email Geeks says they typically build warming schedules based on the recency of last engagements and recommend splitting out segments by Mailbox Provider like Gmail, Yahoo/AOL/Verizon, and Outlook/Hotmail/MSN/Live, plus everyone else. For a brand new IP, starting with 100 emails a day at each ISP is a good approach. They also suggested reaching out to the Outlook postmaster team.

2019-01-01 - Email Geeks

Expert view

Expert from Email Geeks says they look for recipients who engaged in the last X days, adjusting X based on contact source size and activity. If the initial segment is too large, they find other ways to segment or use random sampling to reach the desired size. They aim for a 20% open rate during warming and adjust subsequent segment sizes based on previous day’s results.

2019-01-01 - Email Geeks