Microsoft 365 
What is Exchange Online?
Exchange Online is Microsoft’s cloud-based email service included in all Microsoft 365 plans. It gives each user a professional mailbox (e.g., name@yourcompany.com) with 50GB storage, calendar, and contacts — accessible from Outlook, browser, or mobile.
Step 1 — Add Your Custom Domain
In the Microsoft 365 Admin Center, go to Settings → Domains → Add domain. Enter your company domain (e.g., yourcompany.com) and follow the steps to verify ownership by adding DNS records at your domain registrar.
Step 2 — Update MX Records
After verification, Microsoft will provide MX records. Add these to your domain’s DNS settings to route email to Microsoft 365. Changes can take up to 48 hours to propagate, but usually happen within a few hours.
Step 3 — Access Outlook
Users can access their mailbox immediately at outlook.office.com. To set up the Outlook desktop app, open Outlook and sign in with the Microsoft 365 email address — it auto-configures.
Step 4 — Set Up Mobile Email
On iOS or Android, download the Microsoft Outlook app from the App Store or Google Play. Open it, tap Add Account, enter the Microsoft 365 email and password — done.