Communication services mail delivery

Question

Communication services mail delivery

Sam Achten 0

When sending emails using Azure Communication Services, the mails are often not delivered. They do not end up in spam at the end of the recipient, they are "gone".

Alekhya Vaddepally 1,670 Reputation points Microsoft External Staff Moderator

2025-05-05T11:56:50.29+00:00
Hi Sam Achten,

It seems that you are experiencing some issues with email delivery using Azure communication services, where the messages disappear without reaching the recipient, and are not found in spam. It can be disappointing!

Here are some things that you can check to solve the problem:

Sender and recipient configuration: Ensure that the sender and recipient email addresses are correctly configured and valid. Sometimes a minor typo delivery can cause issues.

Review mail routing: According to documentation, email routing mailbox can be affected by several factors within the transport service. Ensure that mailbox transport submission and delivery services are correctly installed and operated. To confirm this, take a look at the routing table in your active directory that they are directly directed by messages.

SMTP Configuration: Check if there are any SMTP settings that can affect delivery. Ensure that emails are not being filtered or blocked by either azure communication services or exchange by any transport regulations.

Feedback Loop: Sometimes some sending IP can be blacklisted inadvertently. Consider verifying whether your sending address or IP is on any blocklist and fix it if necessary.

Message size and attachment: Make sure the email you are sending is complying with the range of any size. Large attachments can sometimes prevent email from being successfully sent.

Log and Analytics: Review any log available in the azure portal for communication services whether there is error messages related to unspecified email.

If you have already checked them and the issue remains, please provide more information so that I can help you better. Here is some follow -up questions:
What specific error messages, if any, are you receiving while trying to send emails?
Are there specific recipients domains that are constantly problematic, or it affects all recipients?
Have you checked your mail log for any signal of what can happen to messages after being sent?
Are you experimenting with email delivery through a particular application or service configuration?
Hope it helps, and I look forward to your answer!
Sam Achten 0 Reputation points

2025-05-05T12:24:04.12+00:00

We have checked the proposed solutions, but since some of the emails are delivered and some are not, it does not look like a misconfiguration to us. We do not see any error messages whatsoever. Everything looks good, but our clients sometimes do not receive an email. Maybe due to some spam filters somewhere? But the mails are not in the spam folder of the user though...
Alekhya Vaddepally 1,670 Reputation points Microsoft External Staff Moderator

2025-05-06T09:50:22.6066667+00:00

Hi Sam Achten,
We haven’t heard from you on the last response and was just checking back to see if you have a resolution yet. In case if you have any resolution, please do share that same with the community as it can be helpful to others. Otherwise, will respond with more details and we will try to help.
Alekhya Vaddepally 1,670 Reputation points Microsoft External Staff Moderator

2025-05-07T12:31:17.41+00:00

Hi Sam Achten, We haven’t heard from you on the last response and was just checking back to see if you have a resolution yet. In case if you have any resolution, please do share that same with the community as it can be helpful to others. Otherwise, will respond with more details and we will try to help.

2 answers

Your answer

Sam Achten 0 Reputation points

2025-05-05T12:24:04.12+00:00

We have checked the proposed solutions, but since some of the emails are delivered and some are not, it does not look like a misconfiguration to us. We do not see any error messages whatsoever. Everything looks good, but our clients sometimes do not receive an email. Maybe due to some spam filters somewhere? But the mails are not in the spam folder of the user though...
Alekhya Vaddepally 1,670 Reputation points Microsoft External Staff Moderator

2025-05-06T09:50:22.6066667+00:00

Hi Sam Achten,
We haven’t heard from you on the last response and was just checking back to see if you have a resolution yet. In case if you have any resolution, please do share that same with the community as it can be helpful to others. Otherwise, will respond with more details and we will try to help.
Alekhya Vaddepally 1,670 Reputation points Microsoft External Staff Moderator

2025-05-07T12:31:17.41+00:00

Hi Sam Achten, We haven’t heard from you on the last response and was just checking back to see if you have a resolution yet. In case if you have any resolution, please do share that same with the community as it can be helpful to others. Otherwise, will respond with more details and we will try to help.

Answer 1

Based on what you are describing, I would agree that it looks like your Azure Communication Service instance is indeed configured so as to allow sending email. The nature of SMTP means that it can at time be a challenge to troubleshoot delivery issues because of the relay points that exist between originator and recipient and the fact that many of them will be outside of your visibility and control. If your clients are using corporate mail services, one next step would be to have them connect you with their mail server administrators so that they can look for evidence of the message arriving at their end and understand whether it's being filtered and why. Another thing that I would recommend is configuring email logs as described at https://learn.microsoft.com/en-us/azure/communication-services/concepts/analytics/logs/email-logs.

Answer 2

Hi Sam Achten,
Ensure that you have enabled diagnosis logging in Azure Monitor for your communication service resources. It can help in surface delivery events that are not immediately clear.
This distinguishes your domain reputation and gives you more control over deliverance.

Since there is no visual error, microsoft can help detect problematic distribution efforts through the internal log. It can reveal recipient-specific blocks or filtering behavior that are not publicly exposed.
https://learn.microsoft.com/en-us/azure/azure-portal/supportability/how-to-create-azure-support-request

In cases where specific customers do not receive emails, their organization's email can filter the email quietly before reaching the safety gateway (eg, proofpoint, mimicast, microsoft defender) inbox or spam folders. It is helpful to ask the client to check your email log for filtering activities.
if you have any further concerns or queries, please feel free to reach out to us.

Alekhya Vaddepally 1,670 Reputation points Microsoft External Staff Moderator

2025-05-08T19:53:20.3833333+00:00

Hi Sam Achten, We haven’t heard from you on the last response and was just checking back to see if you have a resolution yet. In case if you have any resolution, please do share that same with the community as it can be helpful to others. Otherwise, will respond with more details and we will try to help.

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Communication services mail delivery

2 answers

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