Enhanced SMTP status code · RFC 3463 · IANA
4.4.244 The HVE message can't be submitted because the recipient rate limit was exceeded
The HVE (High Volume Email) service throttled sending: too many messages to too few recipients in a short time.
- Class: Temporary failure
Class 4: a persistent transient failure. The message was fine, but a passing condition delayed or stopped delivery; a later attempt may succeed (RFC 3463 §3.1). The sending server retries on its own for a while.
- Subject: X.4 · Network and routing
Network and routing status (DNS included); under the control of the destination's or an intermediate server's administrator.
How 4.4.244 appears at providers
The exact text from the provider's documentation, as you see it in the bounce, and what it means.
Microsoft 365 / Exchange Online
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450 4.4.244
The HVE message can't be submitted because the recipient rate limit was exceeded.
The HVE (High Volume Email) service throttled sending: too many messages to too few recipients in a short time.
Have the whole error message?
Sources: RFC 5321 · RFC 3463 · RFC 3464 · IANA · Gmail · Microsoft 365 · read on 26 September 2026