How to warm up an email domain and IP address

You set up a new domain. Or you bought a dedicated IP. Or you just moved to a new email platform. Everything is ready, and your list has 40,000 contacts.

So you press “Send” on all of them. Two days later, half your emails are in spam, Gmail is slowing you down, and your new provider wants to talk to you.

This happens because mailbox providers like Gmail, Outlook and Yahoo don’t know you yet. A new sender that suddenly sends thousands of emails looks exactly like a spammer. Warm-up is how you introduce yourself slowly, so they learn to trust you.

This guide shows you how to do it step by step: what to prepare, who to email first, how fast to grow, which numbers to watch, and what to do when something goes wrong.

What is email warm-up?

Email warm-up is the process of building trust for a new or quiet sender. You start with low volume and grow it over days and weeks. SendGrid describes it as a way to gradually increase the volume of email sent through an IP address, so receiving providers can watch how you send and how people react.

Think of it like a new employee at a bank. On day one, nobody gives them the keys to the safe. They get more trust as they show they can handle it.

During warm-up, mailbox providers watch a few simple things:

• Do your emails reach real mailboxes? Many bounces mean a careless sender.
• Do people want them? Opens, replies and clicks are good signs. Spam reports are bad ones.
• Is your sending steady? Sudden jumps look like a hacked account.
• Are you who you say you are? Authentication must pass on every email.

Domain reputation vs IP reputation

Mailbox providers judge two things separately: your domain (like news.example.com) and your IP address (the server your email leaves from).

	Domain reputation	IP reputation
What it is tied to	The domain in your From address and authentication	The sending server’s IP address
Does it move with you?	Yes. It follows you to any provider	No. It stays with the IP
Who builds it?	Always you	On a shared IP, you and other senders. On a dedicated IP, only you
Needs warm-up when	The domain or subdomain is new for sending, or has been quiet	The dedicated IP is new, or has been quiet

The key point: a warm IP does not make a new domain warm. Amazon’s own guide to IP and domain warming says you can have fully warmed IPs and still need to warm a new sending domain. It also notes that shared IP pools are more forgiving, but still need care.

So even if your provider gives you a shared IP that is already warm, your domain still has to earn its own reputation. If you are not sure which IP type you have, see our guide on shared IP vs dedicated IP.

When do you need to warm up?

You need a warm-up whenever mailbox providers see something new or something that has been quiet:

Situation	What needs warming
New domain or new sending subdomain	Domain
New dedicated IP	IP, and the domain if it is new too
Moving to a new email provider	New IPs, and a gradual move of your traffic
Long break from sending	The domain and dedicated IP may need to start again
Big jump in volume (for example, 5,000 a week to 100,000)	The new, higher volume
A new type of email from the same domain	Usually a separate subdomain, warmed on its own

Providers know that new senders need help. Yahoo’s sender FAQ, for example, asks new senders or senders with a new IP who have trouble reaching Yahoo to fill in its Sender Support Request.

Before your first email: the setup checklist

Warm-up fails fast if the basics are broken. Every email you send during warm-up is a test, so make sure each one passes. Gmail’s email sender guidelines list most of these as requirements.

Check	Why it matters
SPF and DKIM for your sending domain	Proves the email really comes from you
DMARC, with the From domain aligned to SPF or DKIM	Required by Gmail, Yahoo and Outlook for bulk senders
Forward and reverse DNS (PTR) for your sending IP	Gmail requires valid DNS records for sending domains or IPs
TLS connection	Gmail asks for encrypted sending
A clear sender name and a working reply-to address	People must recognise you and be able to answer
One-click unsubscribe plus a visible link	Required for marketing mail. An easy exit beats a spam report
Suppression lists loaded	Past unsubscribes, complaints and bounces must never get an email
Reports turned on	You can’t make decisions without bounce, complaint and delay data

Outlook has the same rules. Microsoft announced that domains sending more than 5,000 emails a day to Outlook.com must pass SPF, DKIM and DMARC. If authentication is new to you, start with our guide to SPF, DKIM and DMARC explained.

Choose who gets your first emails

This is the most important decision in your whole warm-up. Your first emails create your first impression, and first impressions are hard to change.

Send first to the people most likely to open, read and reply. Amazon SES’s dedicated IP warm-up guide gives the same advice: send to your most engaged users first, to keep complaints low.

Who goes first, and who waits

Group	When to email them
Opened or clicked in the last 30 days	First
Recent customers and new subscribers who confirmed	First
Engaged 31 to 90 days ago	Next, once the first groups look healthy
Engaged 3 to 6 months ago	Later in the warm-up
No engagement for 6 months or more	Only after warm-up, through a small re-engagement campaign
Unsubscribes, complaints, past hard bounces	Never
Bought, rented or scraped lists	Never

For the quiet contacts at the bottom, follow our guide to handling inactive subscribers and old email lists.

Verify before you send, not after you bounce

During warm-up, every bounce hurts more than usual, because providers have very little history to balance it against. One old segment full of dead addresses can undo a week of careful work.

That’s why email list validation belongs before your first batch. Our guide on how to clean your email list before sending a campaign covers the full process. Here is how MetaLogic MailVexa fits into your warm-up preparation:

1. Exclude first. Load your unsubscribes, complaints and past bounces into MailVexa’s exclude list. They are skipped and marked “ExcludedEmail”, so they can’t slip back into your warm-up groups.
2. Clean. MailVexa removes duplicates and fixes spacing and capital letters.
3. Verify. Each address is checked and sorted into Valid, Risky, Invalid or Unknown, with a reason.
4. Export by group. Export each result group to its own file, and split large files into smaller parts. Small parts are perfect for warm-up batches.

New to the app? Our guide on how to use MailVexa walks through each screen.

Then use the results like this:

MailVexa result	What to do during warm-up
Valid + recently engaged	Your first batches
Valid + not engaged for months	Wait until warm-up is done, then re-engage carefully
Risky (for example catch-all)	Keep out of early batches. Add later, in small groups
Unknown	Keep out for now. Verify again later
Invalid	Remove. Never send

Not sure what each result means? Read email verification results explained, and for the Risky group, what a catch-all address is.

Build your warm-up plan

There is no magic schedule. A good plan starts from your own numbers. Write these down first:

Question	Why it matters
How many emails will you send per campaign, when warm-up is done?	This is your target
How many truly engaged contacts do you have?	This decides how big your first groups can be
What share of your list is Gmail, Outlook and Yahoo?	Each provider builds trust separately
Is the domain new? Is the IP shared or dedicated?	A new domain on a new dedicated IP needs the most patience
Does your provider limit new accounts or run its own warm-up?	Your plan must fit inside their limits
How often will you really send after warm-up?	Warm-up should lead into your normal rhythm

The simple warm-up loop

Every day of warm-up follows the same four steps:

1. Send to a small group of your best contacts.
2. Spread the sending over hours, not seconds.
3. Check bounces, delays and complaints, by mailbox provider.
4. Decide: increase, hold, reduce or pause (see section 09).

Daily volume and sending speed are different things

Sending 2,000 emails in one day is fine. Sending all 2,000 in the first 60 seconds is not. Gmail’s top sender issues page suggests sending at a steady pace, such as one message per second, instead of fast bursts followed by long pauses. It also says steady volume matters most for new domains.

A practical example plan

Here is how one sender might plan it. Imagine an online shop that set up a new sending subdomain. It has 40,000 contacts who agreed to its newsletter, and it wants to send one newsletter a week.

After verification and segmenting, the list looks like this:

• Group A: opened or clicked in the last 30 days, about 6,000
• Group B: engaged 31 to 90 days ago, about 9,000
• Group C: engaged 3 to 6 months ago, about 11,000
• Group D: no engagement for 6 months or more, about 12,000
• Invalid and excluded addresses, about 2,000, already removed

Stage	Who gets email	Example daily volume	Move on when
1. Prepare	Nobody yet	0	Authentication passes on a real test email, suppressions are loaded, the list is verified
2. Start (first days)	Group A only	500 to 1,000, spread over the day	Bounces and complaints are very low, no delays
3. Grow	Rest of A, then B	Increase 25% to 50% a day while signals stay clean	Each provider looks healthy on its own
4. Fix (only if needed)	Back to A only	Hold or reduce	The cause is found and results recover
5. Reach target (weeks 3 to 6)	Add C. Full weekly newsletter	Normal volume	Results stay stable for several sends
After warm-up	Group D, in small re-engagement batches	Small	Only people who respond return to the main list

What to monitor during warm-up

Look at your numbers after every send, for each mailbox provider separately. Gmail can love you while Outlook is still unsure. An average across all providers can hide that.

Signal	What it tells you	Where to see it
Bounces and their reasons	Dead addresses, or blocks because of your reputation	Your email provider’s bounce report
Deferrals (temporary delays)	The provider is slowing you down. You are going too fast	Your provider’s delivery logs
Spam complaints	People don’t want this email	Your provider’s reports, Gmail Postmaster Tools
Authentication results	Whether every email passes SPF, DKIM and DMARC	Postmaster Tools, DMARC reports
Unsubscribes	Interest is dropping in a group	Your provider’s reports
Clicks and replies	Real interest. More reliable than opens	Your provider’s reports

Gmail’s numbers

Gmail asks senders to keep their spam rate below 0.1%, and never let it reach 0.3%. Use Gmail Postmaster Tools to watch it. Google is moving everyone to a newer version of the tool, and its Postmaster Tools update explains that the old domain and IP reputation dashboards are being retired. Focus on spam rate, authentication and compliance status instead.

Microsoft and others

For Outlook.com, Microsoft’s Smart Network Data Services (SNDS) shows data about the IPs you control, which is useful on a dedicated IP. For most other providers, your email provider’s report, split by mailbox provider, is your main view.

Read the delay codes

A temporary error starts with 4. It means “not now, try later”. When Gmail sees an unusual sending rate, it can delay you with a code like 421 4.7.28. Google lists these codes in its Gmail SMTP error reference. If you see many of them, you are growing too fast for that provider.

Increase, hold, reduce or pause?

After every send, use this table to decide your next step. Make the decision for each mailbox provider on its own.

What you see	Decision	What to do
Low bounces, almost no complaints, no delays, real clicks	Increase	Grow the next send by a small step. Add the next engaged group
Some delays at one provider, everything else fine	Hold	Keep the same volume for that provider until delays stop
Complaints rising, or many delays	Reduce	Go back to your most engaged group. Check content and how often you send
Blocks (5xx errors that mention reputation, policy or spam)	Pause for that provider	Stop, read the error text, fix the cause before you send again
Many “user unknown” hard bounces	Pause that segment	Your list has a data problem. Verify it again before sending

Many providers help with this. SendGrid’s Deliverability Insights, for example, shows delivery, bounce and spam report numbers by mailbox provider.

Manual or automated warm-up?

Many email providers can warm up a dedicated IP for you. Here is how some of them work:

Provider	How its automatic warm-up works
Amazon SES (standard dedicated IPs)	On by default. Moves a growing share of your mail to the new IP over about 45 days, while the rest goes through already-warm IPs
Amazon SES (managed dedicated IPs)	Warms up separately for each mailbox provider. Extra mail goes through the shared pool in the early phase
Twilio SendGrid	Limits hourly volume for 41 days. Extra mail uses your other IPs or waits in a queue for up to 72 hours
Mailgun	Grows in stages, with rest periods between them

Which one should you choose?

• Automated is easier and safer for most senders. The provider controls the speed of the IP.
• Manual gives you more control, but every mistake is yours. Amazon warns that if you turn off its automatic warm-up, you are responsible for doing it right.

Migration, transactional email and long breaks

Moving to a new email provider

1. Bring your “do not send” lists. Import unsubscribes, complaints and bounces first.
2. Move traffic gradually. Keep sending most email from the old provider while the new one warms up. Move your most engaged groups first.
3. Pause old automations before you start new ones, so nobody gets the same email twice.
4. Keep the old account until the new one is stable.

Transactional email (receipts, password resets)

Keep important system emails separate from marketing, for example on their own subdomain such as mail.example.com versus news.example.com. This way, a bad marketing week can’t delay a password reset. Amazon’s guide recommends this split as well. Warm up each stream on its own.

After a long break

Reputation fades when you stop sending. SendGrid says to warm an IP up again if you haven’t sent through it for more than 30 days. Postmark’s dedicated IP rules say an IP must be warmed up again if volume stays below 20,000 messages a week for four weeks. After a long break, start again with your most engaged contacts, and verify the list first: addresses die while you are away.

Common warm-up mistakes

Mistake	What happens	Do this instead
Sending to the whole list on day one	Delays, spam folder, blocks	Start with a small engaged group
Starting with your oldest list because it is the biggest	Many bounces and complaints in the first days	Start with your best contacts. Old contacts come last
Skipping verification	Bounces break your warm-up early	Verify the list before the first batch
Following a fixed schedule no matter what	Problems grow with every send	Let results decide each step
Looking only at averages	One provider blocks you and you don’t notice	Check each mailbox provider separately
Sending everything in one fast burst	Rate limits and delays	Spread sending over hours
Changing many things at once	You can’t tell what caused a problem	Change one thing at a time
Stopping after warm-up, then sending a huge campaign weeks later	You lose the trust you built	Keep a steady rhythm
Buying a dedicated IP for low volume	Not enough mail to build trust	Use a shared IP until volume is high and steady

Your warm-up checklist

• SPF, DKIM and DMARC pass on a real test email
• Forward and reverse DNS are set for my sending IP
• One-click unsubscribe and a visible unsubscribe link work
• Unsubscribes, complaints and past bounces are loaded as suppressions
• My list is verified, and Invalid addresses are removed
• Risky and Unknown addresses are kept out of early batches
• My first groups are my most engaged, opted-in contacts
• I spread sending over hours, not seconds
• I check results for each mailbox provider after every send
• I increase only when bounces, complaints and delays stay low
• I know when to hold, reduce or pause
• After warm-up, I keep a steady sending rhythm

Common questions

How long does email warm-up take?

Usually 2 to 6 weeks. Amazon SES and Postmark both give ranges in this window. It can be shorter for a small, very engaged list and longer for a big list or a domain with a bad history.

How many emails should I send on the first day?

Start small, and only to your most engaged contacts. Spamhaus advises no more than 1,000 a day in the first few days of a new or quiet IP. If your engaged group is smaller, start with fewer.

Do I need to warm up my domain if I use a shared IP?

Yes. A shared IP may already be warm, but your domain has its own reputation. A new sending domain still needs to start slowly.

My website domain is old. Do I still need to warm it up?

Yes, if it has never sent bulk email. Providers judge your sending history, not your website’s age.

What if I don’t have an engaged list?

Then build one before you send in volume. Use signup forms with clear permission, start with recent customers, and send small batches. An old or bought list is not a substitute.

I send a weekly newsletter. Do I have to send every day during warm-up?

Not every day. You can split your first newsletters into smaller parts and send them over a few days. After warm-up, go back to your normal weekly rhythm and keep it steady.

I stopped sending for a few weeks. Do I need to start again?

Often, yes. SendGrid suggests warming up again after more than 30 days without sending. Start with your most engaged contacts and grow back step by step.

Does warm-up guarantee my emails reach the inbox?

No. Warm-up gives providers time to judge you fairly. Inbox placement still depends on your list quality, permission, content and how people react.

Sources

Mailbox providers and standards

• Gmail email sender guidelines. Authentication, PTR, TLS, one-click unsubscribe, spam rate, starting with low volume to engaged users, pause after error 4.7.28.
• Top Gmail sender issues. Consistent volume for new domains, one message per second, recovery after deferrals, 25% to 100% daily increases.
• Gmail Postmaster Tools transition. Move to Postmaster Tools v2 and retirement of the reputation dashboards.
• Gmail SMTP errors and codes. Code 421 4.7.28 for unusual sending rates.
• Microsoft: Outlook’s requirements for high-volume senders. SPF, DKIM and DMARC for domains sending more than 5,000 emails a day.
• Microsoft Smart Network Data Services (SNDS). IP data for Outlook.com.
• Yahoo Sender FAQ. Sender Support Request for new senders and new IPs.
• Spamhaus FAQ: marketing email. Warm-up definition, 1,000 emails a day in the first days, warm-up services discouraged, no bought lists.

Email providers

• Amazon SES: Warming up dedicated IP addresses. 2 to 6 weeks, 45-day automatic warm-up, engaged users first.
• Amazon SES: Managed dedicated IPs. Warm-up for each mailbox provider, shared pool for extra mail.
• AWS: Guide to IP and domain warming and migrating to Amazon SES. Domain vs IP warming, best audience first, separate subdomains.
• SendGrid: Warm up an IP address. 41-day automated warm-up, 72-hour queue, re-warm after 30 days.
• SendGrid: Deliverability Insights. Results by mailbox provider.
• Mailgun: Automatic IP Warmup. Stages and rest periods.
• Postmark: Dedicated IPs. 3 to 6 weeks, re-warm rule, minimum volume.

Product

• MetaLogic MailVexa. Desktop email verification software for Windows and macOS.

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We build MetaLogic MailVexa, so weigh our description of it accordingly. We have no commercial relationship with any email provider mentioned in this guide. Provider rules and warm-up schedules were checked in October 2026 and change often, so confirm them on each provider’s own site.