Microsoft (Outlook.com and Microsoft 365) · temporary error
450 4.4.244: HVE: recipient rate limit exceeded
An HVE account sent many messages to a small number of recipients in a short time, and Exchange Online throttled the submission.
- Microsoft
- Provider
- Temporary (4xx)
- Class
- Sources checked
- Author
At a glance
- Code
- 450 4.4.244
- Temporary or permanent
- TemporaryThe sending server keeps the message and tries again later.
- Who has to act
- The sender. The fix is on the sending side: your domain, your server or your list.
- What the server says
450 4.4.244 The HVE message can't be submitted because the recipient rate limit was exceeded.
What it means
HVE is built for volume, but it throttles traffic concentrated on a few recipients. When an HVE account sends many messages to a small number of recipients within a short time window, further submissions get 450 4.4.244. The code is temporary: the application should retry later and space out messages to the same recipients. Repeated hits suggest the application sends one message per event where a digest would serve the recipients better.
Common causes
- An application sends a burst of messages to the same few recipients.
- A loop or retry bug makes the application resend to the same addresses.
How to fix it
- 01Retry the throttled messages after a pause.
- 02Spread messages to the same recipients over a longer period, or combine them into digests.
- 03Check the application for loops or retry bugs.
Sources
What this page rests on, checked on 20 Oct 2026. The explanation is ours; the reply text is the server's.
- Email nondelivery reports and SMTP errors in Exchange Onlinelearn.microsoft.com
Related codes
Further reading
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