All requests from this subscription blocked due to sender reputation. Please review/unblock.

Hii @Nadeesha Chathumal,

Thanks for reaching us regarding the issue of “Requests blocked due to sender reputation” when sending emails through Azure Communication Services (ACS) Email. This behavior occurs when the ACS email service detects a degraded sender reputation and temporarily blocks the subscription from sending further emails to protect deliverability across the ecosystem.

Microsoft enforces sender‑reputation protections to prevent spam, abuse, or patterns that may negatively impact email deliverability. Sender reputation can be affected by:- High bounce rates

• Spam or abuse complaints
• Sudden volume spikes without a warm‑up period
• Low engagement (opens/clicks)
• Out‑of‑date or purchased mailing lists

Even if your DKIM, domain verification, subscription, billing, and configuration settings are correct, a reputation‑based block can still occur.
Required action for the above issue:

• Create a support request here: https://portal.azure.com/#create/Microsoft.Support. Select "Technical" > Communication Services > Email > Delivery/reputation issues. Include: "All requests from this subscription blocked due to sender reputation. Custom domain verified. Subscription ID: [yours], ACS resource: [name]. Please review/unblock."
• Monitor ACS > Email > Domains for "Verified" status. Hold off on sends until lifted, then ramp up slowly (e.g., 50 emails/day) with a cleaned list (<2% bounces).

Reference:
https://learn.microsoft.com/en-us/azure/communication-services/concepts/email/sender-reputation-managed-suppression-list
https://learn.microsoft.com/en-us/azure/communication-services/concepts/email/email-domain-configuration-troubleshooting

Kindly let us know if the above helps or you need further assistance on this issue.

Please "upvote" if the information helped you. This will help us and others in the community as well.

Hi,

I have tried to create a support ticket with "Developer plan". But the portal is not allowing me to create.

PS:
Looks like the Azure Developer Support plan does not allow to directly create technical support tickets in the Azure portal. Technical issues must be raised via Microsoft Q&A (priority support).