Short answer
Microsoft is retiring Azure Communication Services as a standalone offering, and Email is one of the retired services: after September 30, 2028 it won't be available, including its SMTP relay. Existing resources and verified domains keep working until then, and Microsoft begins limiting onboarding to retiring services from October 23, 2026.
Microsoft's suggested replacements, Microsoft 365 High Volume Email and Exchange Online, are built for internal mail and person-to-person mail, not for sending password resets and receipts to your customers. Groundmail is a transactional email API and SMTP relay on mail servers and IP space we own: verify your domain, swap the send call or SMTP settings, and move webhooks and suppressions over at your own pace.
On this page
What Microsoft announced
On September 23, 2026, Microsoft announced the retirement of Azure Communication Services (ACS) as a standalone offering, effective September 30, 2028, in its retirement and breaking changes guide. The Azure Updates entry followed on September 24.
| Date | What happens |
|---|---|
| September 23, 2026 | Retirement announced. ACS Email moves to maintenance: security and critical fixes only, no new features. |
| October 23, 2026 | Microsoft begins limiting onboarding to retiring services. New ACS Email resources can currently still be created, but Microsoft says that can change at any time and recommends migrating rather than starting new solutions on ACS Email. |
| Until September 30, 2028 | Existing ACS resources, connection strings and verified domains keep working, with current SLAs. |
| September 30, 2028 | ACS Email is retired. API and SDK calls may return errors saying the operation isn't supported. |
From Microsoft's retirement and breaking changes guide and Azure Updates.
Last checked on each vendor's public page.
What's affected
Everything you use to send email through ACS retires together:
- The Email REST API and SDKs (
EmailClientin .NET, JavaScript, Python and Java). - SMTP through
smtp.azurecomm.net, which Microsoft lists as one of the ways to send with ACS Email. - Azure managed domains (
…azurecomm.netsender addresses). These belong to Microsoft, so there's nothing to move; you'll send from a domain you own. - Custom domains connected to ACS. The domain is yours and moves with you; the ACS DNS records can come out after you switch.
ACS SMS, WhatsApp, Chat, Rooms, Direct Routing and Job Router retire on the same date. Calling, Call Automation and Call Recording stay available with breaking changes, supported only with Teams-aligned scenarios. This page covers email only.
Why High Volume Email isn't a replacement for customer email
For ACS Email, Microsoft's guide lists two Microsoft alternatives, both of which need Microsoft 365 licensing, and points to third-party providers on Microsoft Marketplace.
| Option | Who it can send to | Built for |
|---|---|---|
| ACS Email (retiring) | Internal and external recipients | App-to-person transactional, bulk and engagement email |
| Microsoft 365 High Volume Email | Internal recipients in your Microsoft 365 tenant only | High-volume operational email from apps and devices, inside the organization |
| Exchange Online | Internal and external, subject to tenant limits | Person-to-person email from licensed mailboxes; rate limits apply by design |
| Groundmail | Anyone, from your verified domain | Transactional email from apps: password resets, sign-in codes, receipts, alerts |
Microsoft rows from the ACS retirement guide and the High Volume Email documentation.
Last checked on each vendor's public page.
Microsoft's High Volume Email page is explicit: "HVE accounts cannot be used for external email delivery." Exchange Online can reach external recipients, but it's mailbox email with per-tenant limits, not an API for sending your app's mail to customers. If your ACS workload sends to people outside your organization, you need a provider.
Pricing: ACS Email vs Groundmail
ACS Email is pay-as-you-go: $0.00025 per email ($0.25 per 1,000) plus $0.00012 per MB transferred, on the Azure pricing page. Groundmail is a monthly plan with included emails.
| Emails per month | Groundmail | ACS Email (100 KB average) |
|---|---|---|
| 50,000 | $20 (Pro) | $13.10 |
| 100,000 | $35 (Pro) | $26.20 |
| 500,000 | $350 (Scale) | $131 |
| 1,000,000 | $650 (Scale) | $262 |
ACS amounts computed from the published rates on the Azure pricing page: emails × $0.00025, plus emails × 0.1 MB × $0.00012. Groundmail prices from our pricing page.
Last checked on each vendor's public page.
Why teams move ACS Email to Groundmail
- Keep managed identity, no API keys. Azure workloads call the Groundmail API with their managed identity or workload identity, the same
DefaultAzureCredentialyou use with ACS today. Nothing to store in Key Vault or rotate. How it works. - Infrastructure we own and operate. Your mail leaves from our mail servers and our IP space. The shared pool carries transactional mail only, and we do the warmup and reputation work.
- A send call without polling.
POST /emailsreturns the email id straight away; delivery, bounces, complaints, opens and clicks arrive as signed webhooks instead of Event Grid subscriptions. - SMTP relay.
smtp.groundmail.devon port 587 with a username and an SMTP credential. No directory application, client secret or role assignment to manage. - Dedicated IPs and dedicated servers. $50/mo per dedicated IP on Scale, with the first included from 500,000 emails a month. Or your own mail server and IPs from $299/mo including 250,000 emails, built, warmed and managed by us.
- Free DMARC monitoring. We read your domain's DMARC reports and show who sends as it and whether they pass, on every plan. Useful while two providers sign for the same domain.
- Tenants for platforms. If you send on behalf of your own customers, each one gets its own domains, suppression list, stats, sending ramp and pause switch. Included on Scale and Dedicated, no per-tenant fee.
- Suppressions handled for you. Hard bounces and complaints are suppressed automatically, and a send to a suppressed address returns
422instead of reaching the mailbox provider. - SDKs and tools. Node, Python, Go, PHP (with Laravel and Symfony Mailer), and Ruby, plus a CLI and an MCP server. From .NET, the HTTP API is one
HttpClientcall.
Groundmail is for transactional email only. Marketing and cold email aren't allowed on our IPs under our Acceptable Use Policy. If you used ACS Email for bulk marketing, pick a marketing email provider for that part.
Moving over
- 1
Verify your domain
Add the domain you send from and publish the DNS records Groundmail shows. Groundmail's DKIM selector differs from ACS's, so both can sign while you switch. If you send from an
…azurecomm.netaddress, pick a domain or subdomain you own. - 2
Swap the send call
senderAddressbecomesfrom,recipients.tobecomesto,content.plainTextandcontent.htmlbecometextandhtml, and attachments keep their base64. Or change your SMTP host, username and password and leave the code alone. - 3
Move delivery events
Register a webhook for the events your Event Grid handler acts on:
email.delivered,email.bounced,email.failed,email.opened,email.clicked. - 4
Bring your suppressions
Export the addresses on your ACS domain suppression lists and add them with
POST /suppressions. - 5
Shift traffic gradually
Send a share of mail through Groundmail behind a flag, watch bounces and complaints, then move the rest and remove the ACS DNS records.
The full field mapping, C#, Node and Python before-and-after code, and the SMTP and suppression details are in the ACS Email migration guide. Create a free account to start with your domain.
Frequently asked questions
When does Azure Communication Services Email stop working?
Microsoft retires ACS Email on September 30, 2028. After that date it won't be available, and API and SDK calls may return errors. Existing resources and verified domains keep working, with current SLAs, until then.
Can I still create a new ACS Email resource?
Currently, yes. Microsoft begins limiting onboarding to retiring services from October 23, 2026, and says new ACS Email onboarding can change at any time. It recommends using the retirement period to migrate rather than starting new solutions on ACS Email.
Is the ACS SMTP relay retiring too?
Yes. SMTP through smtp.azurecomm.net is part of ACS Email, which Microsoft lists as sending by REST API, SDKs and SMTP, and the whole service retires on September 30, 2028. Groundmail's SMTP relay is smtp.groundmail.dev on port 587 with STARTTLS.
Can I use Microsoft 365 High Volume Email instead?
Only for internal mail. Microsoft's documentation says HVE sends to internal recipients within your tenant and that HVE accounts cannot be used for external email delivery. Password resets, receipts and alerts to customers need a provider that sends externally.
What does Microsoft recommend instead of ACS Email?
Its retirement guide lists Microsoft 365 High Volume Email (internal) and Exchange Online, both needing Microsoft 365 licensing, and points to third-party providers on Microsoft Marketplace for external application email.
Is Groundmail cheaper than ACS Email?
No. ACS Email is $0.25 per 1,000 emails plus $0.00012 per MB, so 100,000 small emails cost about $26 a month against $35 on Groundmail Pro. ACS Email stops being available after September 30, 2028, so compare against the providers you can move to.
What happens to my azurecomm.net sender address?
Azure managed domains belong to Microsoft and retire with the service. Groundmail doesn't provide a shared domain for production mail, so verify a domain or subdomain you own, such as notify.yourcompany.com, and update your from addresses.
How do Event Grid delivery reports map to Groundmail?
EmailDeliveryReportReceived with status Delivered, Bounced, Failed or Suppressed maps to the email.delivered, email.bounced, email.failed and email.suppressed webhooks. Engagement reports of type View and Click map to email.opened and email.clicked. Each webhook is a signed JSON event posted to your HTTPS endpoint.
Sources
Facts on this page about other companies' products, prices and policies come from these public pages. They change, so check them before you decide.
- Microsoft Learn: ACS retirement and breaking changes guide
- Azure Updates: ACS standalone services retirement
- Microsoft Learn: What's new in Azure Communication Services
- Microsoft Learn: High Volume Email for Microsoft 365
- Azure Communication Services pricing
- Microsoft Learn: ACS Email SMTP authentication