# Outlook Email Sending Limits: How Many Can You Send?

> How many emails you can send in Outlook per day and per message, what happens when you hit Microsoft 365 limits, and how to stay safely under them.

**TL;DR** (Microsoft's documented defaults, verified July 2026)

- **Microsoft 365 work and school accounts (Exchange Online):** up to **10,000 recipients per rolling 24 hours**, **500 recipients per single message** by default (admins can raise it to 1,000), and a rate limit of 30 messages per minute.
- **Personal Outlook.com accounts:** up to **5,000 recipients per day** for Microsoft 365 subscribers; free and new accounts get significantly less.
- These are Microsoft's limits, not Outlook settings; you cannot raise them yourself, but your admin can adjust some of them.

_You are about to send a big batch of emails from Outlook. How many is too many?_

Here are the numbers that matter, what actually happens when you cross them, and how to run large sends without ever getting close.

## The limits at a glance

| Account type | Recipients per day | Recipients per message | Message size |
| --- | --- | --- | --- |
| Microsoft 365 work / school (Exchange Online) | 10,000 (rolling 24 hours) | 500 default, up to 1,000 if raised by admin | 35 MB default, up to 150 MB if raised by admin |
| Outlook.com with a Microsoft 365 subscription | 5,000 | 500 | 20 MB |
| Outlook.com free account | Lower and variable; new accounts most restricted | Lower | 20 MB |

A few important details:

- The daily limit counts **recipients, not messages**. One email to 500 people uses 500 of your 10,000, and so does 500 individual emails to one person each.
- Exchange Online also limits the **sending rate** to 30 messages per minute; anything faster is throttled and queued, not bounced.
- Organizations additionally have a **tenant-wide external recipient limit** (TERRL) that caps how many external recipients the whole tenant can email per day.
- Tenants can set **lower** limits than these defaults, and brand-new tenants often start restricted. If your numbers look smaller, ask your IT administrator.
- The limits exist to keep Microsoft's servers off spam blocklists, which protects the deliverability of your normal email too.

## What happens if you exceed the limits?

The symptoms differ by which limit you hit:

- **Sending faster than 30 messages per minute:** nothing breaks; Exchange throttles you and messages queue up, sending more slowly.
- **Exceeding the daily recipient quota:** messages bounce with a submission quota error such as **"554 5.2.0 ... SubmissionQuotaExceededException"**, or sit in the Outbox until the rolling 24-hour window frees up capacity.
- **Suspicious sending patterns:** separate from the quotas, Microsoft can block traffic it considers abusive (errors in the 5.7.x range, such as 5.7.708). Repeated violations can get a mailbox **temporarily blocked from sending** until support intervenes.

The daily quota is a rolling 24-hour window, so a blocked send usually recovers on its own within a day. Repeated violations can flag the account, which is much harder to undo, so the goal is never to hit the wall in the first place.

## How to send a large campaign without hitting limits

If you are sending a [mass email](https://www.securemailmerge.com/knowledge/how-to-send-mass-email-outlook/) or a mail merge, each recipient is one email, so a 2,000-row spreadsheet means 2,000 recipients against your daily quota. To stay comfortably inside it:

- **Cap your own daily volume.** SecureMailMerge can [limit how many emails are sent each day](https://www.securemailmerge.com/help/sending-mail-merge-during-specific-hours/); anything over the cap automatically moves to the next sending day.
- **Slow down the rate.** [Add a delay between messages](https://www.securemailmerge.com/help/sending-mail-merge-with-delay-between-messages/) so your send trickles out instead of bursting.
- **Pick sending days and hours.** Restrict sending to [specific weekdays and a time window](https://www.securemailmerge.com/help/sending-mail-merge-during-specific-hours/), for example business mornings only.
- **Split very large lists** across several days; with a daily cap this happens automatically.

> **Campaigns that respect the limits**
>
> SecureMailMerge sends through your own Microsoft 365 mailbox and lets you set a daily cap, sending delay, weekday selection, and time window per campaign, so even multi-thousand recipient sends stay inside Microsoft's rules. See [mail merge campaign limits](https://www.securemailmerge.com/help/maximum-recipients-limits/) for product specifics.

## Frequently asked questions

### How many emails can I send at once in Outlook?

A single email can go to 500 recipients by default on Microsoft 365 work and school plans (up to 1,000 if your admin raises it). Across a rolling 24-hour window, the ceiling is 10,000 recipients. Personal Outlook.com accounts with a Microsoft 365 subscription get up to 5,000 recipients per day; free accounts get significantly less.

### How many emails can I send per day with a mail merge?

The same 10,000-recipient daily quota applies; a mail merge to 1,000 rows counts as 1,000 recipients. Use a daily cap and sending delay to pace larger campaigns.

### Can I increase my Outlook sending limit?

Not as a user. Some limits (like message size) can be raised by your Microsoft 365 administrator, and higher-volume needs are what dedicated bulk services or Azure Communication Services are for. For typical mail merge volumes, staying under the standard limits with pacing is enough.

### Why is my limit lower than 10,000?

New tenants often start with reduced limits, and administrators can configure stricter ones. Check with your IT team; the numbers above are Microsoft's defaults, not guarantees.