What are the email sending limits in Microsoft 365 and Google Workspace?

Microsoft 365 and Google Workspace mailboxes are built for people, not mailing lists. Both cap how much each user can send, and both block the account for up to a day when it goes over. That surprises people who send one big announcement, and it's also one of the first signs that an account has been hijacked to send spam.

This guide lists the current limits on both platforms, explains what each bounce means, and covers how to send bulk mail without hitting them.

What are the Microsoft 365 sending limits?

Microsoft publishes these per-mailbox limits for Exchange Online at the time of writing (October 2026) (Microsoft Learn):

Microsoft says the recipient rate limit and message rate limit "are hard limits enforced at the service level and can't be increased." Admins can only set lower limits in the outbound spam policy: an external limit per hour, an internal limit per hour and a daily limit, each from 0 to 10,000, where 0 means the service default. Our anti-spam policy guide lists Microsoft's recommended values.

How Microsoft counts recipients

The limit counts recipients, not messages. One email to 500 people uses 500 of your 10,000. Microsoft's Exchange Online limits page gives an example: a user who sends to 5,000 recipients at 9:00, 2,500 at 10:00 and 2,500 at 11:00 can't send again until 9:00 the next day.

Distribution groups matter. A group stored in your organization's address book counts as one recipient. A contact group in a user's own Contacts folder counts each member.

Tenant-wide limits

Two more limits apply to the whole organization:

• Tenant External Recipient Rate Limit (TERRL). The maximum number of external recipients the whole tenant can send to per day. It "scales automatically with the number of licenses," and trial tenants are capped at 5,000 external recipients per day. Unlike the mailbox limit, TERRL counts each member of a distribution group. You can see your number in the Tenant Outbound External Recipients report under Reports > Mail flow in the Exchange admin center.
• The onmicrosoft.com domain. Mail sent from your default onmicrosoft.com address is limited to 100 external recipients per organization in a rolling 24 hours. Add and use your own domain. See DMARC for onmicrosoft.com domains for why that domain shouldn't send anyway.

What happened to the 2,000 external recipient limit?

You may have read that Microsoft would limit each mailbox to 2,000 external recipients a day. That plan, the Mailbox External Recipient Rate limit, was postponed several times. On January 6, 2026, Microsoft updated its Message Center notice to say it had "decided not to proceed with the rollout of this limit," and the Exchange team published a post titled Exchange Online canceling the Mailbox External Recipient Rate Limit. At the time of writing (October 2026), Microsoft's limits documentation lists no per-mailbox external limit. The 10,000-recipient limit and TERRL still apply.

What are the Google Workspace sending limits?

Google's published limits per user, at the time of writing (October 2026) (Google Workspace Admin Help):

Google says "limits per day are applied over a rolling 24-hour period, not a set time of day," and that "sending limits can change without notice."

Trial accounts

Trial limits aren't raised during the free trial. Google raises them automatically after the account converts to a paid subscription and has paid a minimum cumulative amount, and says that can take up to 75 days after the threshold is reached. If you're migrating a business to Google Workspace, don't plan a big announcement from a trial account.

The SMTP relay service has separate limits

Devices and applications that send through Google's SMTP relay service (smtp-relay.gmail.com) have their own limits. Google says each user "can send up to 10,000 messages in a 24-hour period," to no more than 10,000 unique recipients, with 100 recipients per SMTP transaction. Relay and Gmail user limits are "independent and counted separately from each other." Limits are lower for trial accounts and for accounts that haven't paid a bill yet (Google Workspace Admin Help).

Microsoft 365 and Google Workspace compared

What happens when you exceed a limit?

Microsoft 365 bounces

The first two come from Microsoft's SMTP submission throttling article and submission quota NDR article. When a user exceeds the recipient rate limit, Microsoft says they "might also appear on the Restricted entities page," and the Email sending limit exceeded alert fires. Our guide to a Microsoft 365 user blocked from sending covers unblocking. If the whole tenant is blocked for spam or reputation, see 550 5.7.708.

Google Workspace bounces

Users see messages such as "You have reached a limit for sending email," "You reached a Gmail sending limit" or "You exceeded the maximum recipients." Over SMTP the reply is 550 5.4.5 Daily user sending limit exceeded. Google says users "can't send new messages for up to 24 hours," but can still receive mail. Accounts that exceed limits might be suspended, and accounts that send spam can be permanently restricted.

Don't confuse these with deferrals from the receiving side. A Gmail reply such as 421 4.7.28 means Gmail is rate limiting your server's traffic as a recipient, not that your own account hit a quota.

Hitting a limit without sending much

Both Microsoft and Google treat unexpected volume as a sign of compromise. Microsoft's NDR article says that if you didn't send the messages, you should reset your password, scan your devices, and follow its compromised account steps, because "the attacker might have configured other settings on your mailbox." Check the Sent folder, inbox rules and forwarding before unblocking anyone. Our compromised account checklist has the full procedure.

How should you send bulk email instead?

Microsoft says "Exchange Online isn't designed for bulk mailing scenarios," and points to Azure Communication Services Email or a non-Microsoft bulk email provider (Microsoft Learn). Google's limits make the same point. A mailbox is the wrong tool for newsletters, marketing or high-volume notifications.

1. Pick a dedicated sending service for newsletters, marketing and high-volume transactional mail.
2. Send from a subdomain, such as news.example.com, so bulk reputation doesn't affect your staff's mail. Our guide to separate subdomains for transactional and marketing mail explains how.
3. Authenticate it. Set up SPF and DKIM for the service on that subdomain, aligned with your DMARC policy.
4. Meet the bulk sender rules. Gmail, Yahoo and Microsoft require authentication, easy unsubscribe and low complaint rates from large senders. See bulk sender requirements and one-click unsubscribe.
5. Ramp up gradually on a new domain or IP. Our warm-up guide covers the schedule.
6. Keep lists clean. Microsoft's own advice is to remove invalid and bouncing addresses, honor unsubscribes immediately and use confirmed opt-in.

For apps and devices

Scanners, line-of-business apps and alerts still count against a mailbox's limits when they send through it. Microsoft suggests using a different mailbox for each application or device, or an SMTP relay connector, and designing apps to retry when throttled. Our scan-to-email guide compares the options. For Google Workspace, the SMTP relay service has higher, separate limits.

A smart host can also carry low-volume application mail with DKIM signing; see what a smart host is. iBlockSpam's outbound relay includes 500 messages a month per domain, which suits a website form or a few devices, not a newsletter.

Next steps

• Check which users and apps send the most mail, using message trace or Email Log Search.
• In Microsoft 365, set explicit outbound spam policy limits below the service maximums, and make sure the Email sending limit exceeded alert reaches a real person.
• Move newsletters and campaigns to a dedicated sending service on a subdomain.
• Look up any bounce code you receive in the SMTP error code tool.
• Test your domain's authentication with the Email Health Check before any large send.

Browse more guides on running email day to day.