If your emails are hitting spam folders after switching to a new IP address, or you're wondering whether a dedicated IP address is worth the extra cost, this guide explains the mechanics clearly.
Table of Contents
- What is an IP address in email sending?
- What is IP warming?
- Shared IP vs. dedicated IP address: what's the difference?
- When do you actually need a dedicated IP?
- How IP warming works in practice
- What is the difference between IP warming and domain warming?
- Dedicated IP setup: what's involved
- Brevo's approach: shared IPs that work
- Summary: what to take away
What is an IP address in email sending?
Every email you send originates from a server with an internet protocol (IP) address. That IP address is part of what mailbox providers (Gmail, Outlook, Yahoo, and others) evaluate when deciding whether to deliver your message to the inbox, filter it to spam, or reject it entirely.
Over time, an IP address builds a reputation based on sending behavior: bounce rates, spam complaint rates, engagement rates, and email volume consistency. A new IP address (one with no history) is an unknown quantity. Mailbox providers are cautious with unknown quantities, and that caution directly affects your inbox placement.
This is the core problem IP warming solves.
What is IP warming?
IP warming is the process of gradually increasing your sending volume from a new IP address over several weeks so that mailbox providers can observe your sending behavior before you hit them with full volume. It's structured and requires a slow, deliberate ramp-up. No shortcuts.
When you start sending from a new IP, internet service providers (ISPs) have no basis for trust. If you immediately blast 500,000 emails from a brand-new IP address, ISPs treat that sudden high-volume spike as suspicious activity and will trigger automatic spam filters. Sending thousands of emails from an unknown IP without IP warming is a reliable way to damage your sender reputation before you've even established it.
By gradually increasing email volume, starting with a few hundred emails per day to your most engaged subscribers and doubling your sending volume each week, you give mailbox providers time to observe that your email is legitimate and wanted. Positive signals (opens, clicks, low spam complaints) build trust. That trust translates into consistent inbox placement at scale.
A standard IP warm-up process schedule looks roughly like this:
The exact numbers depend on your list size and target sending volume. The principle is consistency and gradual growth. Maintaining a consistent sending schedule is what helps establish a predictable pattern for ISPs.
How long does IP warming take?
The IP warming process typically takes between two and six weeks, depending on your total audience size, sending frequency, and engagement levels. For higher-volume senders aiming at 100,000+ emails per week, expect the full warming period to run closer to six to eight weeks. There's no shortcut. Any tool claiming to warm up an IP in days is not describing a real warm-up.
Shared IP vs. dedicated IP address: what's the difference?
Most email senders use a shared IP address, an IP shared with many other senders on the same platform. Email service providers like Brevo manage pools of shared IPs and actively monitor all senders on them. If one sender on a shared IP behaves badly, the provider removes them before the bad behavior damages the shared IP address's reputation or affects other senders using the same IP.
A dedicated IP address is assigned exclusively to your account. Your sender reputation is entirely your own, for better or worse. You're not affected by what other senders on the same IP do, because there are no other senders on that IP.
The intuitive assumption is that dedicated = better. That's not always true.
A shared IP with a well-managed provider already has a strong, established sender reputation built over years of sending. A fresh dedicated IP starts from zero and requires you to build that reputation yourself, which takes time and a consistent sending volume. On a shared IP, you're essentially borrowing a good reputation while your own sending behavior contributes to maintaining it. Using a dedicated IP without the volume to support it can actually hurt your email deliverability rather than improve it.
When do you actually need a dedicated IP?
The answer is: at higher volumes than most people think.
A dedicated IP address makes sense if you're sending at least 50,000–100,000 emails per week, consistently.
Here's why: maintaining a dedicated IP's sending reputation requires regular, high-volume sending. Mailbox providers want to see consistent patterns from the same IP address. If your IP sends 50,000 emails one week and then goes quiet for three weeks, the signal degrades. The rule of thumb is sending at least three times per week during the warming period and beyond to keep the reputation healthy.
You likely need a dedicated IP if:
- You send 50,000+ emails per week on a regular schedule
- You're in a regulated industry (financial services, healthcare) and want full control over your sending infrastructure
- Your email marketing strategy requires isolating transactional email from marketing emails, keeping them on separate IPs so a spike in marketing volume doesn't affect transactional deliverability
- You have a strong track record and want your sender reputation entirely decoupled from other senders
You probably don't need a dedicated IP if:
- You send fewer than 50,000 emails per week
- Your sending is seasonal or irregular
- You're just starting out and building a list
- You're already getting strong inbox placement on a shared IP
Brevo's shared IPs deliver a 99%+ inbox rate. For the vast majority of users (businesses sending tens of thousands of emails per month rather than per week), using a shared IP on a properly managed platform is the right choice.
Need a dedicated IP after all? In Brevo's Enterprise plan, one dedicated IP is included at no additional cost. Additional dedicated IPs can be purchased as add-ons (for Professional and Enterprise plans). Find out how you can set it up here.
How IP warming works in practice
If you do graduate to a dedicated IP address, here's what the IP warming process actually involves.
Authenticate your domain before you start
Before you send a single email from your new IP address, ensure your domain is fully authenticated. This means setting up three email authentication protocols: Sender Policy Framework (SPF), DomainKeys Identified Mail (DKIM), and Domain-based Message Authentication (DMARC). These authentication protocols prove your legitimacy to mailbox providers and reduce the risk of spoofing.
A TXT record in your DNS is used to publish your SPF policy. DKIM adds a cryptographic signature to your outgoing mail. DMARC ties them together with a policy that tells providers what to do when authentication fails. None of these replace IP warming. They're prerequisites for it. Misconfigured email authentication on a dedicated IP can create deliverability problems worse than a shared IP.
Find out more about SPF, DKIM and DMARC in our dedicated article.
Start with your most engaged subscribers
The first emails from a new IP should go to your most engaged subscribers, people who have opened or clicked in the past 30 days. High engagement rates in the early days of the warming process are critical for generating the positive signals that build trust with mailbox providers.
Separate your active subscribers from inactive subscribers before you begin. Active subscribers (those who regularly engage with your email campaigns) are your warm-up list. Inactive subscribers (no opens or clicks in six months or more) should wait until the IP is fully warmed. Sending to disengaged contacts early risks generating the bounce rates and spam complaints that raise red flags with ISPs.
Also, clean your list for spam traps before starting the warming process. A spam trap hit on a brand-new IP address can cause serious deliverability problems that take weeks to recover from. Good list hygiene isn't optional. It's part of successful IP warming.
Segment your list: active vs. inactive subscribers
A practical approach is to divide your contact list into tiers:
- Tier 1: Opened or clicked in the last 30 days (use these first)
- Tier 2: Engaged in the past 90 days (introduce in weeks 3–4)
- Tier 3: Engaged in the past 180 days (introduce in weeks 5–6)
- Tier 4: Inactive subscribers (no engagement in 6+ months), send to last once the IP is fully warmed
This tiered approach ensures you're generating positive signals at each stage of the warming process, which steadily builds your IP reputation with mailbox providers.
Monitor key engagement metrics closely
During the warming period, watch these metrics daily:
- Bounce rates: Keep hard bounces below 2%. Above that, pause and clean your list.
- Spam complaints: The target deliverability rate during email campaigns should be 96% to 99%, with spam complaint rates kept at or below 0.2%.
- Deferral rate: Temporary deferrals indicate a mailbox provider is cautious about your IP. Sustained high deferral rates mean you should slow down your volume increase.
- Open rates and click-through rates: Low engagement on a new IP is a signal for providers that your email may not be wanted. Use your most engaged subscribers first to avoid this.
Related: 10 best email deliverability tools.
Using Google Postmaster Tools
Google Postmaster Tools is a free tool that lets you monitor your IP reputation and domain reputation with Gmail directly. During the warming period, it's one of the most useful ways to see how Gmail is classifying your sending IP. Set it up before you start sending and check it daily during the first few weeks. If your IP reputation drops to "Bad" or "Low," pause and investigate before continuing to send emails.
What to do if metrics go wrong
If spam complaint rates spike above 0.2% or bounce rates climb past 2%, don't push through. Pause sending, diagnose the issue (bad list segment, weak subject lines, non-permission contacts), and fix it before resuming. Continuing to send with poor metrics deepens the damage to your sender reputation and extends the time needed to recover.
Don't pause sending
One of the most common warm-up mistakes is going quiet for a few weeks in the middle of the process. If you pause sending for more than 30 days, your IP's reputation can degrade and you may effectively have to restart the warming process. Maintaining consistency in your email volume and sending frequency is what builds the trust that leads to strong inbox placement.
What is the difference between IP warming and domain warming?
IP warming is sometimes confused with domain warming, which is a related but distinct process.
IP warming is about building reputation for the sending IP address. Domain warming is about building reputation for your sending domain (the domain in your From address). A brand-new domain, whether you're switching from an old domain or launching a new brand, also needs to build reputation with mailbox providers, regardless of whether you're on a shared or dedicated IP.
If you're both new to a platform and using a new domain, you're doing both warm-ups simultaneously. That's manageable, but it means being even more conservative in the early weeks and paying close attention to engagement metrics.
For most Brevo users on a shared IP, domain warming is the more immediately relevant concern: getting your email authentication properly configured, starting with engaged contacts, and building a sending history under your domain. The IP reputation is handled by Brevo's infrastructure.
Dedicated IP setup: what's involved
Setting up a dedicated IP address with Brevo requires more than just activating the option. You'll need to configure seven DNS records for full authentication:
- A record: maps your domain to the IP
- MX record: for inbound mail routing
- CNAME: for tracking links on your dedicated IP
- DKIM: cryptographic signature for email authentication
- SPF: TXT record that authorizes your IP to send on behalf of your domain
- DMARC: policy that tells mailbox providers what to do if authentication fails
Getting these records right before you begin the IP warming process is essential. Brevo's email deliverability services documentation walks through each record in detail.
Brevo's approach: shared IPs that work
Brevo's infrastructure uses optimized pools of shared IPs that are actively managed. Brevo monitors sender behavior across its platform and acts on bad actors before they affect shared pool reputation, which is why most Brevo customers achieve strong email deliverability without ever needing to think about IP management.
The dedicated IP option is available for customers who genuinely need it. If you're unsure which is right for you, the threshold is simple: if you're regularly sending 100,000+ emails per week and want full control over your sending reputation, a dedicated IP address is worth evaluating. Otherwise, stay on shared and focus your email marketing strategy on what actually moves the needle for most senders: list quality, email authentication, and engagement.
If you're running into deliverability issues, Brevo's email deliverability best practices guide and Brevo's email API are good next steps.
Summary: what to take away
IP warming is the process of gradually building sender reputation on a new IP address by starting with low volumes to your most engaged subscribers and increasing email volume incrementally over several weeks.
Dedicated IP addresses are not universally better than shared IPs. They require significant sending volume (50,000–100,000+ emails/week), consistent sending frequency, proper email authentication, and a full warming period to deliver their potential benefit. Using a dedicated IP below these thresholds can actively hurt your inbox placement.
Most senders, including businesses sending tens of thousands of emails per month, are better served by a well-managed shared IP. Brevo's shared infrastructure is built to improve deliverability without requiring you to manage IP reputation yourself.
If you want to test Brevo's email deliverability before committing, the free plan gives you 300 emails per day with full API and SMTP access, no credit card required.
