Using Custom Email Aliases in Azure Communication Services

2025-10-27 2 min read Azure Azure Communication Service Email "Erwin Bierens"

Using Custom Email Aliases in Azure Communication Services (ACS)

If you’ve started experimenting with Azure Communication Services (ACS) Email, you’ve probably noticed a small but annoying limitation in the Azure Portal:
by default, you can only send emails from the DoNotReply@yourdomain.com address.

But what if you want to send newsletters from newsletter@yourdomain.com, or customer notifications from support@yourdomain.com?
Unfortunately, the Azure Portal doesn’t (yet) allow you to configure additional sender aliases.

The Hidden CLI Command

Luckily, this is where the Azure CLI comes to the rescue.
You can create new sender usernames (aliases) directly via the CLI using the following command:

  az communication email domain sender-username create \
  --email-service-name "acs-mailer-01" \
  --resource-group "RG_EB_01" \
  --domain-name "erwinbierens.com" \
  --sender-username "newsletter" \
  --username "newsletter" \
  --display-name "erwinbierens.com - Newsletter"

What This Command Does

Let’s break it down:

–email-service-name → the name of your ACS Email service (including the domain if nested)

–resource-group → your Azure resource group name

–domain-name → the verified domain you’ve connected to ACS (e.g. erwinbierens.com)

–sender-username → the alias you want to send from (e.g. newsletter)

–username → a friendly name for this alias (often the same as the sender username)

Once executed, this command registers newsletter@erwinbierens.com as a valid sender identity. You can now use it programmatically through the ACS Email SDK or REST API when sending messages.

Verify Your New Alias After running the command, you can confirm your new alias with:

  az communication email domain sender-username list \
  --email-service-name "acs-mailer-01/erwinbierens.com" \
  --resource-group "RG_EB_01" \
  --domain-name "erwinbierens.com"

This will return a list of all active sender usernames linked to your domain.

Why This Matters

Having multiple sender identities is crucial for:

separating transactional and marketing emails
improving deliverability and domain reputation
staying compliant with DMARC and branding requirements

Until Microsoft adds this feature to the Azure Portal, this CLI method is the only way to manage sender aliases effectively.