Introduction
Before staff send mail as [email protected], you must verify your domain in Microsoft 365 and point DNS records at Microsoft. This guide covers the steps SMBs in Thailand and Singapore follow — whether you buy licenses from us or already have a tenant.
What you need before you start
- A domain name you control (e.g.
.co.th,.com.sg,.com) - Access to your DNS host (Cloudflare, GoDaddy, Thai hosting panel, etc.)
- Global admin rights in Microsoft 365 (or your IT partner)
- At least one Business or Enterprise license assigned to create mailboxes
Step 1 — Add the domain in Microsoft 365
- Sign in to Microsoft 365 admin center as admin.
- Go to Settings → Domains → Add domain.
- Enter your domain (e.g.
yourcompany.co.th) and choose I'll manage my own DNS records if you use external DNS (most SMEs do).
Microsoft generates the records you must publish.
Step 2 — Verify ownership (TXT record)
Add the TXT record Microsoft shows — usually at the root (@) or _dnsauth subdomain. Propagation can take 15 minutes to 48 hours depending on your DNS provider.
Click Verify in the admin center once TXT resolves.
Step 3 — Email routing (MX record)
Point inbound mail to Exchange Online. Microsoft provides an MX target like yourdomain-com.mail.protection.outlook.com with priority 0.
Important: Remove old MX records pointing to Gmail, cPanel, or previous host — otherwise mail splits or bounces.
Step 4 — SPF, DKIM, and DMARC (deliverability)
| Record | Purpose |
|---|---|
| SPF (TXT) | Authorises Microsoft to send mail for your domain |
| DKIM (CNAME) | Signs outbound messages — reduces spam folder risk |
| DMARC (TXT) | Policy for failed authentication (start with p=none, tighten later) |
Enable DKIM in Defender → Email authentication after CNAME records propagate.
Step 5 — Create users and assign licenses
- Users → Active users → Add a user
- Assign the correct SKU (Basic, Standard, etc.)
- User signs in at office.com with the new UPN (
[email protected])
Unlicensed users cannot get a full Exchange mailbox.
Common mistakes
- Leaving old MX — mail never reaches Outlook
- Typos in TXT — domain never verifies
- Using Personal/Family licenses for company
@domainmail — not supported; you need Business or Enterprise - Skipping DKIM — outbound mail to customers lands in spam
When to get help
If you migrate from Google Workspace, cPanel, or on-prem Exchange, DNS cutover should be planned — see our Google to M365 checklist or contact us for a cutover window.