How Many Warm-up Emails Per Day for a New Microsoft 365 or Outlook Inbox?

Short answer: Start with 30 warm-up emails per day for a new Microsoft 365 or Outlook inbox if your domain reputation is neutral or healthy. Use Ramp-up for at least 14 days so you do not jump to 30 on day one.

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Keep a simple 1:1 rule where warm-up volume matches cold email volume, and do not exceed 50 cold emails/day or 50 warm-up emails/day.

The goal is steady, predictable behavior.Microsoft inboxes tend to be less forgiving when volume increases too quickly, so the safest plan is to start conservative and cap early-stage volume.

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The 1:1 warm-up rule for Microsoft inboxes

A practical rule experienced senders follow is 1:1 warm-up to cold volume.

That means:

• Planning to send 30 cold emails/day? Warm up around 30/day
• Planning to send 50 cold emails/day? Warm up around 50/day

This matters because it avoids a common mismatch: warm-up stays low, but cold email ramps up fast. That jump is exactly what can create early filtering or throttling.

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Learn what email warm-up is actually doing behind the scenes: What Is Email Warm-Up & How It Works

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Recommended limits for Microsoft 365 and Outlook

For most new Microsoft mailboxes, a safe operating range looks like this:

• Safe baseline: 30 warm-up emails per day
• Early-stage cap: 50 warm-up emails per day
• Cold email cap: 50 cold emails per day

If you want one simple rule to publish and stand behind:

Do not exceed 50 cold emails/day and 50 warm-up emails/day on Microsoft mailboxes.

Important: This assumes your domain reputation is neutral or healthy. If you are recovering from deliverability issues, seeing spam placement, or working with a brand-new domain, ramp more slowly and consider a lower starting target.

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Learn how domain reputation is established and repaired: How Domain Reputation Affects Email Deliverability

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Ramp-up matters more on Microsoft

Even if your target is 30/day, do not start there on day one.

A safe ramp-up approach

• Use at least a 14-day ramp-up period
• Increase daily volume gradually
• Avoid predictable step patterns (like the exact same increase every day)

The goal is to look natural, not scripted.

How ramp-up should behave in practice

If ramp-up looks too perfect, it can create an unnatural sending signature. Randomized increases tend to look more organic over time.

In Mailivery, you set your target and enableRamp-up. Daily increases are randomized so volume builds gradually without looking formulaic.

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Learn how email ramp-up works and why it matters: What Is Email Ramp-Up and How It Works

How to set this up (quick checklist)

Warm-up volume is controlled by your Emails Per Day setting.

Recommended settings for a new Microsoft 365 or Outlook inbox

• Target (Emails Per Day): 30
• Ramp-up: On
• Ramp-up period: at least 14 days
• Sending schedule: only during your normal business hours
• Do not exceed: 50/day for cold, 50/day for warm-up

Once your target is set, leave ramp-up on until you reach the daily limit.

Review Microsoft’s official warm-up process for email sending: Microsoft’s Email Warm-Up Process for Sender Reputation

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When to start cold emailing on Microsoft

This is where most deliverability problems begin.

If your domain is a few months old

• Warmup for at least 14 days before starting cold email

If your domain is brand new

• Warmup for 30 to 60 days before starting cold email

A new domain has little to no trust. Treat it like a fresh credit score.

Microsoft-specific warning signs you are scaling too fast

If any of these happen, hold volume steady for several days or reduce it:

• Messages start landing in Junk more often
• You see sending slowdowns or delays
• Bounce or rejection messages increase
• Replies and positive engagement drop as volume rises

Do not respond by pushing harder. Stabilize first, then scale.

FAQ

Is 30 warm-up emails per day enough for Microsoft 365 or Outlook?

For many senders, yes. It is a safe baseline that supports steady reputation building. If your cold volume is closer to 50/day, you can scale toward 50/day after a proper ramp-up.

Why cap Microsoft warm-up and cold sending at 50/day?

Because Microsoft mailboxes often react poorly to early volume spikes. A50/day cap keeps you in a safer lane while you build consistent sending history and engagement.

Should warm-up match cold email volume exactly?

It does not have to be perfect, but staying close to 1:1 is a reliable guideline. If you plan to send 40 cold emails/day, warming up around 40/day is usually more stable than warming up at 10/day.

Should I keep warm-up running long-term?

 In most cases, yes. Ongoing warm-up helps maintain consistent engagement and keeps sending behavior steady.