Outlook itself has no recipient limit. The limit comes from the mail server behind your account, so it is the same in classic Outlook, new Outlook, Outlook on the web and Mac. What changes is the account type: Exchange Online (work or school) and Outlook.com (personal) have different numbers. In this guide, I’ll show each limit, the error it produces, and what to do when you hit one.
Quick Answer: With a Microsoft 365 work or school mailbox, you can send to 500 recipients per message (To, Cc and Bcc together). An admin can raise that to 1,000. On top of that, each user can send to 10,000 recipients per 24 hours and 30 messages per minute. These limits are the same in every Outlook client.
Which Limit Did I Hit?
Start here if a message bounced or a user is blocked. The error code usually points straight at the limit.
| Limit | What triggers it | Error or symptom | Who can change it |
|---|---|---|---|
| Per-message recipients | More than 500 addresses in To, Cc and Bcc combined | Message bounces with a “too many recipients” type error | Admin, up to 1,000 per mailbox |
| Recipients per day | More than 10,000 recipients in a rolling 24 hours | Sending stops until the count drops below 10,000 | Nobody, it is a hard limit |
| Messages per minute | More than 30 messages in one minute | Delay only, no bounce | Nobody |
| Tenant external recipients per day | The whole company sends too many external recipients in 24 hours | 550 5.7.233 | Not adjustable, scales with licences |
| onmicrosoft.com cap | More than 100 external recipients in 24 hours from a default onmicrosoft.com address | 550 5.7.236 | Send from your own domain instead |
| Outbound spam policy | The user sends too much, or looks like spam | 5.1.8, and the user shows under Restricted entities | Admin, in the Defender portal |
The numbers come from Microsoft’s Exchange Online limits page and the outbound sending limits troubleshooting article.
The 500 Recipients Per Message Limit
The default is 500, and it counts To, Cc and Bcc together. Putting 500 addresses in each field does not give you 1,500. Bcc hides the addresses from the other readers, but every Bcc address still counts toward the 500 and toward the daily total.
Admins can change this per mailbox, anywhere from 1 to 1,000. It is the same on Business, E1, E3, E5 and F3 plans, because the limit belongs to the service, not the licence. Encrypted messages have a lower limit, about 200 recipients.
If you are the admin, Microsoft documents how to change the limit on the same Exchange Online limits page linked above. I would not raise it for everyone. Raising it for the one mailbox that really needs it is safer.
10,000 Recipients a Day and 30 Messages a Minute
Both limits apply per user.
- The 10,000 limit is a rolling 24 hours. It counts recipients, not messages, so one message to 400 people uses 400 of the 10,000. After you hit it, you can send again once the past-24-hour count falls under 10,000.
- The 30 per minute limit throttles you. Extra messages are held and sent in the following minutes, so you see a delay, not a bounce. A script or a scanner that fires many messages at once runs into this first.
- If a user sends from another mailbox with Send As or Send on Behalf permission, the sends count against the user who clicked send, not the mailbox they sent from.
If mail looks stuck after a big send, check the Outbox first, then ask your admin whether the user was restricted. If a message to a large list bounced or went to junk, check its email headers with my free tool to see where it was stopped and whether SPF, DKIM and DMARC passed.
Do Groups and Distribution Lists Count as One Recipient?
It depends on where the list lives.
A distribution list or group stored in your organization’s address book counts as one recipient, for the 500 limit and for the 10,000 daily limit. Exchange expands it on the server.
A personal distribution list or contact group, the kind you build in your own Contacts folder, is different. Every member counts. A personal list of 600 people fails the 500 limit even though it looks like one name.
The tenant external recipient limit is the exception to the first rule. It counts group members individually after expansion, nested groups included.
For a large audience inside the company, an address-book group is the right tool. For a large audience outside it, see the bulk mail section below.
The Tenant External Recipient Limit (550 5.7.233)
This one is per company, not per user. It counts external recipients across the whole tenant in a sliding 24 hours, and the allowance scales with the number of licences. Trial tenants are capped at 5,000 a day. When the tenant hits it, users get 550 5.7.233.
Admins can see the usage in the Exchange admin center under Reports > Mail flow > Tenant Outbound External Recipients. The troubleshooting article linked above explains the report and the alerts.
The onmicrosoft.com Trap on New Tenants
Mail sent from a default address that ends in onmicrosoft.com is limited to 100 external recipients per organization in 24 hours. Internal mail is not affected. The bounce is 550 5.7.236, and group members are counted after expansion.
Microsoft started this with trial tenants in October 2025 and phased it in for larger tenants through 1 June 2026, so it applies everywhere now. If you still send from an onmicrosoft.com address, move to your own domain. Microsoft explains the change in Limiting onmicrosoft.com domain usage for sending emails.
The 2,000 External Recipient Limit That Was Cancelled
You may still read that Exchange Online will cap each mailbox at 2,000 external recipients a day. Microsoft announced it in 2024 and delayed it several times. On 6 January 2026 Microsoft published a post cancelling it, titled Exchange Online canceling the Mailbox External Recipient Rate Limit.
I could not read the full body of Microsoft’s post, so the details here follow press coverage (Petri, The Register, Office 365 for IT Pros). They report the same thing: the 2,000 limit is off, and the 10,000 recipient limit and the tenant external limit stay. Do not plan around 2,000. Do not tell users it is gone for good either, because Microsoft says it may bring a different approach later.
Meeting Invites, Outlook.com and Bulk Mail
Meeting invites. Any outgoing meeting request, including updates and cancellations, can go to at most 5,000 recipients.
Outlook.com (personal accounts). Microsoft publishes numbers for Microsoft 365 subscribers only: 5,000 recipients a day, 500 per message, and 1,000 a day to people you have not emailed before. Limits vary with account history, and a new account starts lower. Microsoft does not publish the free-account numbers, and the “100 per message” figure you see elsewhere is not on Microsoft’s sending limits page.
Bulk mail. Microsoft says Exchange Online is not designed for bulk mailing and points to a third-party sender or Azure Communication Services Email. Mail that goes over the service limits is blocked. It is not quietly sent through the high-risk delivery pool, the separate set of IPs Microsoft uses for mail it judges to be spam or low quality. For a newsletter, use a proper sending service. For internal announcements, use an address-book group.
If the problem is the mailbox itself rather than the sending limit, here is how to see your Outlook mailbox size. If a delegate sends from a shared mailbox, see who has access to it.
FAQ
How Many People Can I Bcc in Outlook?
Bcc shares the 500 recipient limit with To and Cc. You can put all 500 in Bcc, but they still count toward your 10,000 a day.
Is the Recipient Limit Different in New Outlook?
No. New Outlook, classic Outlook and Outlook on the web all send through Exchange Online, so the server limits apply the same way. I found no source that says otherwise.
How Do I Send an Email to More Than 500 People in Outlook?
Use an address-book group (one recipient), ask your admin to raise your mailbox limit toward 1,000, or send in batches. For external lists, use a bulk sending service.
What Happens When I Hit the Daily Limit?
You cannot send until your count in the past 24 hours drops under 10,000. If the outbound spam policy restricted you, the bounce is 5.1.8 and the user appears under Restricted entities, which only an admin can review.
