Unable to send email from Outlook - using Microsoft Developer sandbox

Question

Hello Team,

We got Microsoft Developer Sandbox program in which I am having 16 test users but unable to send any email from any account although able to receive email - Please help to resolve this issue this is a blocker in our project and need to send email for testing feature.

My Sandbox details: Admin user: * PII Removed

Domain: * PII Removed

Answer 1

Hi Santosh Ulbetti 

To better understand your situation, could you clarify whether this domain is the primary domain or a subdomain within your tenant? 

Case 1: This domain is a subdomain

-Go to Exchange admin center https://admin.cloud.microsoft/exchange#/homepage> Mail flow > Accepted Domain > Choose Domain > Select Internal Relay and tick "Accept mail for all subdomains" then try to send emails.

Case 2: This domain is primary domain

• If a subdomain already exists: Try sending email using the subdomain (make sure DKIM and DMARC are set up successful for the subdomain) to see if the email can be sent successfully. If not, check whether you receive a similar error. 
• If no subdomain exists yet: Try creating a custom domain following this guide: Add your custom domain - Microsoft Entra | Microsoft > Then use that subdomain to send email and test whether it works.  Then, Go to Exchange admin center > Mail flow > Accepted Domain > Choose Domain > Select Internal Relay and tick "Accept mail for all subdomains" >Then, try sending an email again.

I'm looking forward to your update! 

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Answer 2

Hi @Santosh Ulbetti 

Thank you for reaching out to the Microsoft Q&A forum. 

Based on your subscription, could you kindly provide the Non-Delivery Report (NDR) message? This will help me better understand the issue and assist you more effectively. 

Additionally, may I ask if you have sent any emails from this user account? If so, could you please confirm how many messages were sent in total? 

I look forward to your response. 

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