2. How to Manage Mailboxes in Exchange Online: Aliases, Forwarding, Restrictions, and Message Size (Video in Khmer)
Learn manage mailbox in Exchange Online step by step in very simple English with 4 Khmer video: add alias email address, configure mail forwarding, set delivery restriction, and change message size limit, plus easy tips.
2026-10-26 ยท 4 min read
Hello my friend! ๐ฌ In last lesson we create user and give license. Now user have mailbox โ so today we learn how to manage mailbox in Exchange Online. This lesson have 4 video in Khmer.
What You Will Learn
- โ Add alias (extra email address) for mailbox
- โ Forward email to other mailbox
- โ Control who can send email to mailbox
- โ Change max message size for send and receive
All setting in this lesson do in Exchange admin center: admin.exchange.microsoft.com.
06 - Add Alias Email Address for Mailbox (10:06)
แแถแแแแแแแแแแแ แแแแแถแแ user in Exchange Online
Alias is extra email address for same mailbox. Example: Sok have sok@company.com, and you add alias info@company.com. Email send to both address go into Sok mailbox โ only one inbox.
07 - Configure Mail Forwarding (7:17)
Forwarding make Exchange send copy of email to other mailbox auto. Very useful when staff go holiday or leave company โ their email still reach somebody.
You can choose keep a copy in original mailbox too, so no email lost.
08 - Configure Mail Delivery Restriction (6:06)
แแแแแแแถแแแแแพ Email แแแแปแ Exchange Online
Delivery restriction control who can send email to this mailbox. Example: only staff inside company can send to hr@company.com, and people outside cannot. Or block email from some sender.
09 - Configure Message Size (8:14)
แแแแแแแแ แแแแแพแแถแแแแแปแ Exchange Online
Message size is max size of one email (with attach file) that user can send or receive. You can make it bigger for user who send big file, or smaller for save space.
Quick Summary
| Setting | What it do | Example |
|---|---|---|
| Alias | Extra email address for same mailbox | info@company.com go to Sok inbox |
| Forwarding | Send copy of email to other mailbox | Email of staff on holiday go to manager |
| Delivery restriction | Control who can send to mailbox | Only internal staff can email HR |
| Message size | Max size of one email | Allow designer send bigger file |
Tips
- Alias is free! It not need extra license. Use alias for
info@,sales@,support@instead of buy new user. - Alias must use domain you already add in Microsoft 365. You cannot add alias with domain you not own.
- Forward to external email (like Gmail) is often blocked by default in Microsoft 365 for security. If forward not work, check outbound spam policy.
- When forward email, tick "keep a copy" so original mailbox still have the mail.
- After change setting, wait some minute. Exchange Online sometime need time for apply change.
- Don't make message size too big. Big email make mailbox full fast. For big file, share OneDrive link better.
- Write down every change you make (who, what, when). Later when user ask "why I not get email?", you can check easy.
Conclusion
Now you can manage mailbox like real admin: add alias, forward email, control who can send, and set message size. These setting use a lot in real company. Watch all 4 video and practice in your Microsoft 365 trial. Keep learning my friend! ๐ก