5.7.703 Microsoft bounce: blocked by tenant allow list
What 5.7.703 means
The recipient address or domain is on your organisation's Tenant Allow/Block List, so the whole message is blocked.
Message text
Your message can't be delivered because messages to <recipients> are blocked by your organization using Tenant Allow Block List.
Common causes of 5.7.703
- A recipient or domain in the message is on the tenant allow/block list
- One blocked recipient blocks the whole message
How to fix 5.7.703
- Ask an email administrator in the sending organisation to review the tenant allow/block list.
- Remove the blocked recipient from the message and send the rest separately.
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How to read 5.7.703
The second part, 5.7.703, is an enhanced status code (RFC 3463 §2) written class.subject.detail. Class 5 is a Permanent failure (5xx): the command was rejected and the sender should not repeat it unchanged (RFC 5321 §4.2.1; RFC 3463 §2).. Subject 7 is security or policy: authentication, authorization or policy refused the message. The detail number refines the subject, and providers may define details of their own, which is why one code can read differently at Gmail, Microsoft and Yahoo.
Do not keep resending the same message: a permanent failure repeats until the cause is fixed. Correct the cause, then send a new message.
Official source: learn.microsoft.com. Last verified 2026-10-20.
Related guides
- How to create an SPF record (syntax and examples)
- How DKIM works and how to publish a DKIM record
- How to set up a DMARC record, from p=none to p=reject
Related codes
- 5.7.0 SMTP: security status
- 5.7.1 SMTP: delivery not authorized
- 5.7.23 SMTP: SPF validation failed
- 5.7.25 SMTP: reverse DNS failed
- 5.7.26 SMTP: authentication failed
- 5.7.27 SMTP: sender has null MX
FAQ
What does 5.7.703 mean?
The recipient address or domain is on your organisation's Tenant Allow/Block List, so the whole message is blocked. This is a permanent failure.
How do I fix 5.7.703?
Ask an email administrator in the sending organisation to review the tenant allow/block list. Remove the blocked recipient from the message and send the rest separately.
Is 5.7.703 permanent, and should I retry?
5.7.703 is a permanent failure, so retrying the same message will fail again. Fix the cause first, then send a new message.