Enhanced SMTP status code · RFC 3463 · IANA
5.7.243 This tenant is blocked from using HVE
The account or organisation is not set up for, or not allowed to use, the HVE service; the administrator has to fix it.
- Class: Permanent failure
Class 5: a permanent failure. Resending the same message will not help: something about the message, the sender or the destination must change (RFC 3463 §3.1).
- Subject: X.7 · Security and policy
Policies (per-host or per-recipient filters) and cryptographic operations; up to the sender, the recipient or both.
How 5.7.243 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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550 5.7.243
This tenant is blocked from using HVE. Contact your administrator.
The account or organisation is not set up for, or not allowed to use, the HVE service; the administrator has to fix it.
Have the whole error message?
Sources: RFC 5321 · RFC 3463 · RFC 3464 · IANA · Gmail · Microsoft 365 · read on 26 September 2026