Outlook Sending Limits 2026: Exchange, Gmail and Yahoo Rules

What are Outlook's sending limits in 2026?

A Microsoft 365 business mailbox can send to 10,000 recipients a day. Microsoft Learn's Exchange Online limits page, last updated 19 October 2026, gives the same sending limits for every Microsoft 365 and Office 365 plan in its table, from Business Basic to Enterprise E5, and for Exchange Online Plan 1 and Plan 2:

• Recipient rate limit: 10,000 recipients a day per mailbox. It counts the past 24 hours. Once a mailbox reaches it, the mailbox can't send until the count drops back below the limit.
• Message rate limit: 30 messages a minute. Microsoft says messages above that rate are throttled and carried over to the following minutes, which typically does not block the account. Messages submitted by an SMTP client above that rate are rejected and must be retried.
• Recipients per message: up to 1,000. Admins can set it anywhere between 1 and 1,000.
• Tenant External Recipient Rate Limit (TERRL). A separate cap on external recipients for the whole organisation, which depends on how many licences the tenant has. It is covered in detail below.

Microsoft says Exchange Online isn't suited to bulk mailing. The same page recommends Azure Communication Services Email for bulk or high-volume email to external recipients, and says outbound mail from the default onmicrosoft.com domain is limited to 100 external recipients per organisation in a 24-hour window.

Personal Outlook.com accounts have their own limits. Microsoft Support's Outlook.com sending limits page lists, for Microsoft 365 subscribers, 5,000 recipients a day, 500 recipients per message and 1,000 non-relationship recipients a day, which is Microsoft's term for people you have never emailed before. It says limits are lower for non-subscribers and vary with usage history.

What happened to Microsoft's 2,000 external recipient limit?

Microsoft cancelled it before it took effect. On 6 January 2026 the Exchange Team announced that the Mailbox External Recipient Rate Limit in Exchange Online "is being canceled indefinitely at this time". It said customers had told it the limit created significant operational challenges.

The schedule had already moved before that:

• 15 April 2024. Microsoft announced an External Recipient Rate (ERR) limit of 2,000 external recipients per mailbox in 24 hours, starting with newly created tenants on 1 January 2025 and reaching existing tenants between July and December 2025 (the post as archived on 22 April 2024).
• 16 December 2024. Microsoft delayed the limit by about six months, to October 2025 for trial and new tenants and April 2026 for existing tenants (archived 1 January 2025).
• 25 June 2025. It delayed it again by about six months, to April 2026 for trial and new tenants and October 2026 for existing tenants (archived 2 November 2025).
• 6 January 2026. A note at the top of the live post now says the limit has been cancelled and will not go into effect, and that the post is kept for historical purposes.

As planned, the 2,000 cap would have sat inside the 10,000-recipient daily limit and counted every recipient, not unique ones: Microsoft's example was that 100 emails to the same 5 external people would count as 500.

What stays the same: the cancellation notice says the Recipient Rate Limit and the Tenant-level External Recipient Rate Limit are unchanged. Microsoft also kept its stated goals of fighting spam and stopping line-of-business apps from sending bulk email through Exchange Online, and said it would pursue them with "smarter, more adaptive approaches that protect the service while respecting your operational needs."

How does Microsoft's tenant external recipient limit work?

TERRL caps how many external recipients a whole Microsoft 365 organisation can send to in a 24-hour sliding window. Microsoft's TERRL announcement, published 24 February 2025 and updated 13 August 2026, says it is now fully implemented for tenants in the worldwide environment, and gives the formula for the standard quota: 500 × (number of non-trial email licences to the power of 0.7) + 9,500.

Microsoft's own sample values:

• 1 licence: 10,000 external recipients a day
• 10 licences: 12,006
• 25 licences: 14,259
• 100 licences: 22,059

Three details from the same post matter for small teams. It counts every recipient: 1,000 messages to the same external address count as 1,000. Messages to a distribution group are counted after the group is expanded, so a group with 1,000 external members counts as 1,000. And once the tenant is over its quota, further external mail bounces with error 550 5.7.233 (550 5.7.232 for trial tenants) until the 24-hour total drops below the limit. Admins can see the quota and usage in the Exchange admin center, under Reports, then Mail flow.

Since its August 2026 update, the TERRL post also lists lower quotas for new and trial tenants, with quota changes rolling out from 14 September 2026. A tenant under 31 days old gets 10% of its standard quota and one aged 31 to 60 days gets 25%, so a new one-licence tenant starts at 1,000 external recipients a day. Trial tenants get 500 a day, whatever their licence count. The Learn limits page still says 5,000, the trial figure the TERRL post gave as archived in July 2026. On a trial, plan for 500.

What are Google Workspace's sending limits?

Google Workspace allows each user to send 2,000 messages a day, according to Google's Gmail sending limits in Google Workspace page, last updated 13 October 2026. Google says the limits apply over a rolling 24 hours, not a set time of day, and can change without notice.

• Messages per user per day: 2,000; 1,500 when sent by mail merge; 500 for trial accounts.
• Recipients per message: 2,000 in total, with at most 500 external.
• Total recipients per day: 10,000 (1,500 for mail merge).
• External recipients per day: 3,000.
• Unique recipients per day: 3,000, of which 2,000 external, or 500 external on a trial account.

Messages sent from a user's alias, by delegated users and by the vacation responder all count toward the user's limits. When a user hits one of these limits, Google says they can't send new messages for up to 24 hours, though they can still receive email and use other Google services. Google also warns that accounts that send spam might be permanently restricted from sending.

For cold email, two of these numbers bind first: 2,000 messages and 2,000 unique external recipients a day. Follow-ups use up messages; new people use up unique recipients. A sequence that emails the same person three times in a day uses three messages but one unique recipient.

Every 2026 limit and bulk-sender rule in one table

Every row below comes from the provider's own page, checked on 20 October 2026. Sending caps are what your mailbox can send; bulk-sender rules are what the receiving provider demands.

What do Gmail, Yahoo and Outlook.com require from bulk senders?

All three want authenticated mail from large senders, and Gmail and Yahoo also set a 0.3% spam-rate ceiling. The details and dates differ.

Gmail. Since 1 February 2024, Google's email sender guidelines require every sender to set up SPF or DKIM, have valid forward and reverse DNS, use TLS and keep the spam rate reported in Postmaster Tools below 0.3%. Senders of more than 5,000 messages a day to Gmail accounts must also set up SPF, DKIM and DMARC, align the From domain, and support one-click unsubscribe on marketing and subscribed messages. The sender guidelines FAQ adds that volume is counted across the primary domain, that a sender who crosses the line once is a bulk sender permanently, and that from November 2025 Gmail is ramping up enforcement, including temporary and permanent rejections. Google recommends keeping the spam rate below 0.1%.

One scope note: the guidelines cover mail sent to personal Gmail accounts (@gmail.com and @googlemail.com). The FAQ says they don't apply to messages sent to Google Workspace accounts. They also tell senders not to email people who didn't sign up.

Yahoo. Yahoo began enforcing its sender requirements in February 2024, rolling enforcement out gradually, with one-click unsubscribe enforced from June 2024. They apply to every domain Yahoo Mail hosts, AOL included. All senders need SPF or DKIM and a spam rate below 0.3%. Bulk senders also need SPF and DKIM, a DMARC policy of at least p=none that passes, a list-unsubscribe header with one-click support, and unsubscribes honoured within 2 days. Yahoo says it will not specify a volume threshold for bulk.

Outlook.com. Microsoft announced on 2 April 2025 that domains sending over 5,000 emails a day to Outlook.com, Hotmail and Live addresses must pass SPF and DKIM and publish DMARC of at least p=none, aligned with SPF or DKIM. Its 29 April update says failing messages are rejected with error 550 5.7.515 from 5 May 2025. The Outlook.com Postmaster site still says they go to the junk folder, with rejection to follow. Microsoft recommends a working unsubscribe link and list hygiene but publishes no spam-rate number in that announcement.

What to check this week

Find your real cap, then make sure every sending domain passes all three providers' authentication rules. Each step below takes under an hour.

1. Read your tenant's quota

   On Microsoft 365, open the Exchange admin center, go to Reports, then Mail flow, and check your tenant's external recipient quota and how much of it you use. On Google Workspace, check whether any sending user is still on a trial account with the 500-a-day limit.

   15 minutes

2. Stop sending from onmicrosoft.com

   If any mailbox still sends from the default onmicrosoft.com domain, add your own domain. Microsoft limits that default domain to 100 external recipients per organisation a day.

   Microsoft 365 only

3. Set SPF, DKIM and DMARC on every sending domain

   SPF and DKIM passing, plus a DMARC policy of at least p=none aligned with them, meets the authentication part of the bulk-sender rules at Gmail, Yahoo and Outlook.com, whatever your volume.

   30 minutes per domain

4. Watch your spam rate

   Register your domain in Google Postmaster Tools and Yahoo's Complaint Feedback Loop. Keep Gmail's reported rate below 0.1% and never let it reach 0.3%.

   Weekly check

5. Count every recipient

   Microsoft's tenant limit counts every recipient, not unique ones, so a three-step sequence to 100 people uses up to 300 of it over the life of the sequence. Plan daily volume against the smallest cap that applies to you. Our guide to cold email sequences covers spacing the steps.

   Before each campaign

Then write fewer, better emails. Our cold email templates are a starting point, and if email is one of several channels, see multichannel outreach.

Frequently asked questions

Sources

1. Microsoft Learn: Exchange Online limits (updated 19 Oct 2026)
2. Exchange Team Blog: Exchange Online canceling the Mailbox External Recipient Rate Limit (published 6 Jan 2026)
3. Exchange Team Blog: Exchange Online to introduce External Recipient Rate Limit (published 15 Apr 2024, updated 6 Jan 2026)
4. Internet Archive: the same post as of 22 April 2024 (archived 22 Apr 2024)
5. Exchange Team Blog: Introducing Exchange Online Tenant Outbound Email Limits (published 24 Feb 2025, updated 13 Aug 2026)
6. Microsoft Support: Sending limits in Outlook.com (checked 20 Oct 2026)
7. Google Workspace Help: Gmail sending limits in Google Workspace (updated 13 Oct 2026)
8. Gmail Help: Email sender guidelines (checked 20 Oct 2026)
9. Gmail Help: Email sender guidelines FAQ (checked 20 Oct 2026)
10. Yahoo Sender Hub: Sender Requirements & Recommendations (checked 20 Oct 2026)
11. Yahoo Sender Hub: FAQs (checked 20 Oct 2026)
12. Microsoft Defender for Office 365 Blog: Outlook's New Requirements for High-Volume Senders (published 2 Apr 2025, updated 29 Apr 2025)
13. Outlook.com Postmaster (checked 20 Oct 2026)
14. Internet Archive: Exchange Online to introduce External Recipient Rate Limit, as of 1 January 2025 (archived 1 Jan 2025 (post updated 17 Dec 2024))
15. Internet Archive: Exchange Online to introduce External Recipient Rate Limit, as of 2 November 2025 (archived 2 Nov 2025 (post updated 25 Jun 2025))
16. Internet Archive: Introducing Exchange Online Tenant Outbound Email Limits, as of 11 July 2026 (archived 11 Jul 2026)