Azure Communication Services Email is retiring: what to do next

On September 23, 2026, Microsoft announced that Azure Communication Services (ACS) will be retired as a standalone offering on September 30, 2028. Email is on the list of retired services, alongside SMS, WhatsApp, Chat and Rooms. The Azure Updates entry followed on September 24.

If your app sends password resets, receipts or alerts through ACS Email, nothing breaks today, and you have almost two years. This post sets out what Microsoft has said, what it means for email, and how to plan the move without a rush.

The dates

One detail worth getting right, because early coverage didn't: the October 23 date is when Microsoft starts limiting onboarding, and the first hard restriction is on phone numbers. For Email, Microsoft's FAQ says you can currently still create new ACS Email resources, that this "is subject to change at any time", and that it recommends using the retirement period to migrate rather than to start new solutions.

What's affected for email

Everything you send through:

• The ACS Email REST API and SDKs. EmailClient in .NET, JavaScript, Python and Java.
• SMTP through smtp.azurecomm.net. Microsoft lists REST, SDKs and SMTP as the ways to send with ACS Email, and the service retires as a whole.
• Azure managed domains. Sender addresses on …azurecomm.net belong to Microsoft and go away with the service.
• Custom domains. Your domain is yours. The ACS-specific DNS records can be removed once you've switched.

Microsoft also says data and telemetry for retired services will be decommissioned after the retirement date, so export any delivery logs you need to keep before then.

What Microsoft recommends instead

For Email, Microsoft's guide lists Microsoft 365 High Volume Email (HVE) and Exchange Online, both requiring Microsoft 365 licensing, and points to third-party providers on Microsoft Marketplace.

Read the fine print before you plan around HVE. Microsoft's High Volume Email documentation says its recipient scope is internal recipients within your tenant only, and that "HVE accounts cannot be used for external email delivery." Exchange Online can send externally, but it's built for person-to-person mail from licensed mailboxes, with rate limits by design.

So if ACS Email sends mail from your app to your customers, there's no Microsoft product that does the same job. You need an email provider.

A plan that doesn't need a weekend

You have time, so use it to switch carefully:

1. Pick a provider and verify your domain there first. DKIM records from different providers use different selectors, so ACS and the new provider can both sign for your domain while you move. Merge the new provider's SPF include into your existing record rather than adding a second SPF record.
2. Replace azurecomm.net senders. If you send from an Azure managed domain, choose a domain or subdomain you own, such as notify.yourcompany.com, and update your from addresses.
3. Swap the send call, or just the SMTP settings. Most apps have one helper that sends email. If you send over SMTP, changing host, username and password is often the whole code change.
4. Recreate your delivery events. ACS reports delivery through Event Grid (EmailDeliveryReportReceived). Point the new provider's webhooks at the same handler and map the statuses.
5. Bring your suppression list. Export the addresses on your ACS suppression lists and import them, so you don't re-send to addresses that already bounced or opted out.
6. Move traffic gradually. Send a share of mail through the new provider behind a flag, watch bounce and complaint rates at your normal volume, then move the rest and remove the ACS DNS records.

We wrote up the general version of this order in how to switch transactional email providers without downtime.

Moving to Groundmail

Groundmail is a transactional email API and SMTP relay that runs on mail servers and IP space we own. For ACS Email users, the move is mostly mechanical:

• senderAddress, recipients.to, content.subject, content.plainText and content.html become from, to, subject, text and html on POST /emails. Attachments keep their base64 content.
• There's no operation to poll: the send returns the email id, and delivery, bounce, complaint, open and click events arrive as signed webhooks.
• SMTP is smtp.groundmail.dev on port 587 with a username and an SMTP credential, with no directory application or client secret to manage.
• Free DMARC monitoring shows every source sending as your domain while two providers are signing.

The ACS Email migration guide has the field-by-field mapping and before-and-after code for C#, Node.js and Python. For the retirement facts side by side with prices and features, see Azure Communication Services Email alternative.

To be straightforward about price: ACS Email is $0.25 per 1,000 emails plus data transfer, which is cheaper than Groundmail at every volume. It also has an end date. Groundmail's Free plan covers 3,000 emails a month, and paid plans start at $20 a month for 50,000. Groundmail is for transactional email only; if you also used ACS for marketing campaigns, plan a separate home for those.