Outlook Custom Domain: What Still Works After 2023

A lot of how-to articles about using Outlook with your own domain are out of date. They describe a feature in Outlook.com, “personalized email addresses”, that let Microsoft 365 Family users attach their domain to a free-looking mailbox. Microsoft stopped new sign-ups for it in late 2023. If you’re following an older guide and can’t find the button, that’s why.

Here is what works for an Outlook custom domain in 2026.

What happened to personalized addresses in Outlook.com

Microsoft’s support pages state that from 30 November 2023 Microsoft 365 Personal and Family subscribers can no longer create new personalized email addresses in Outlook.com. Addresses that were already set up keep working. If you remove one, you can’t add it back.

So the old route is closed for newcomers. Two routes remain.

Route 1: Outlook app with an IMAP mailbox

You get a mailbox on your domain from a web host or a mail provider. Then you add it to Outlook like any other account. IMAP (a protocol that keeps mail on the server and syncs folders) means your phone and laptop see the same messages.

What you need from your mail host

Where to add the account

The menus vary by app version, roughly:

New Outlook for Windows:  Settings > Accounts > Email accounts > Add account
Classic Outlook (Windows): File > Add Account
Outlook for Mac:           Outlook > Settings > Accounts > +
Outlook iOS / Android:     Settings > Add mail account

Enter your domain address. Outlook tries to detect the settings automatically. If it can’t, pick IMAP and enter the values from the table above.

Many hosts publish an autodiscover or autoconfig record so mail apps find the settings on their own. If yours does, the setup takes about two minutes.

Limits of the IMAP route

• Calendar and contacts don’t sync with the domain mailbox. They stay with whichever account you use for them.
• Webmail is your host’s, not Outlook.com.
• Storage is whatever the host gives you.

For one person that’s usually fine.

Route 2: Microsoft 365 business with your domain

With a Microsoft 365 business plan your domain address is a full Exchange mailbox: mail, calendar and contacts in one place, usable in all Outlook apps and Outlook on the web.

Adding the domain in the admin centre

admin.microsoft.com
 └─ Settings
     └─ Domains
         └─ Add domain

Microsoft then asks you to prove ownership and to add DNS records at your registrar.

; Verification (value shown in admin centre)
tomreid.co.uk.   3600  IN  TXT    "MS=ms12345678"

; Mail delivery (exact host shown in admin centre)
tomreid.co.uk.   3600  IN  MX     0 tomreid-co-uk.mail.protection.outlook.com.

; SPF
tomreid.co.uk.   3600  IN  TXT    "v=spf1 include:spf.protection.outlook.com -all"

; Autodiscover for Outlook apps
autodiscover.tomreid.co.uk.  3600  IN  CNAME  autodiscover.outlook.com.

These are example values. Copy the real ones from the admin centre. For some newer setups Microsoft shows an MX host ending in mx.microsoft instead of mail.protection.outlook.com. Use whatever it lists.

After that, enable DKIM in the Microsoft Defender portal (two CNAME records) and add a DMARC record. Without them, mail to Gmail and Yahoo addresses is more likely to land in spam.

Which route should you pick?

If you’re comparing ecosystems, the Gmail custom domain guide covers the Google side. For all options, including cheaper mail-only providers, see email with your own domain. If you just want a few addresses delivered to an existing inbox, email forwarding for a custom domain is the lightest setup.

Moving away from an old personalized address

If you still have a personalized Outlook.com address from before the cutoff, it keeps working. The risk is the day you want to change something. Removing the domain from Outlook.com is a one-way step, so plan a move before you touch it:

1. Set up the new mailbox first, either at a mail host (route 1) or in Microsoft 365 business (route 2).
2. Export or copy your old mail. With both accounts added to the Outlook desktop app, you can drag folders from one to the other.
3. Lower the TTL of your MX records to 300 seconds a day in advance, so the switch spreads quickly.
4. Change the MX, SPF and autodiscover records to the new provider.
5. Only then remove the domain from Outlook.com.

The domain itself doesn’t need to move for any of this. But you do need to be able to edit its DNS records, so check where it’s actually registered and that you can log in there. If you can’t, sort that out first.

Common problems

Outlook keeps asking for the password. Often the SMTP port and encryption don’t match. Try 587 with STARTTLS.

Mail arrives but sending fails. Some hosts need “My outgoing server requires authentication” switched on, using the same login as incoming.

Microsoft 365 says the domain is already in use. It may be attached to another Microsoft tenant, for example an old trial. That has to be removed there first.

You’ll need the domain before any of this. Search for tomreid.co.uk with your own name, look at .co.uk prices, or open the price list for every extension.

Step by step

1. Get a mailbox on your domainCreate a mailbox at your web host or a mail provider, or buy a Microsoft 365 business plan.
2. For IMAP: note the server detailsWrite down the IMAP and SMTP server names, ports and your password from the mail host.
3. Open account settings in OutlookIn new Outlook for Windows go to Settings, Accounts, Email accounts, Add account. On other platforms use the equivalent Add account option.
4. Enter your domain addressType [email protected], choose IMAP if Outlook doesn't detect the settings, and fill in the server details.
5. For Microsoft 365: add the domain in the admin centreIn admin.microsoft.com open Settings, Domains, Add domain and follow the verification and DNS steps.
6. Send a test messageSend mail from and to the new address and check that it appears in Sent Items.