How to Designate a Permitted Sender in Office 365: A Step-by-Step Guide to Managing Email Senders

Designating a permitted sender in Office 365—now known as Microsoft 365—is an essential step for organizations aiming to ensure important emails aren’t mistakenly marked as spam or quarantined. The process involves adding specific email addresses or domains to what’s called the “Allow List” (Safe Senders) in Exchange Online Protection. Here’s how you can do it:

1. Log in to Microsoft 365 Admin Center: Head to admin.microsoft.com using your admin credentials.
2. Navigate to Exchange Admin Center (EAC): Under "Admin centers," click "Exchange."
3. Access Anti-Spam Policies: In the EAC, find the “Mail flow” section, then select “rules” or “policies” depending on your interface version.
4. Edit the Default Policy or Create a New One:
5. For global whitelisting, select the default anti-spam inbound policy or create a new custom one.
6. Click “Edit policy” and go to the “Allowed and blocked senders and domains” settings.
7. Add Permitted Senders: Enter specific email addresses (like jane@example.com) or a full domain (example.com) under the “Allow” list. Save your changes.
8. Optional—Transport Rules: For advanced exceptions, create a mail flow rule that bypasses spam filtering based on sender, keywords, or other conditions.

After following these steps, designated senders or domains will be recognized as trustworthy, helping inboxes stay clear of misplaced mail. As a designer, I see systems like these as analogous to thoughtful space planning—just as we zone rooms for optimal workflow and comfort, proper whitelisting ensures communications flow smoothly within your digital “space.” If you’re managing shared workspaces or collaborative rooms, you might find a room planner just as essential for organizing people as permitted sender lists are for email.

Tips 1:

When updating allow lists, always review them regularly to remove obsolete addresses or domains for optimal security. Also, communicate these changes to end users so they know which senders are officially recognized and what to do if an email is still blocked inadvertently.

FAQ

Q: Can I whitelist an entire domain in Office 365?

A: Yes, by adding the domain (e.g., example.com) in the “Allow” section of your spam filter policy.

Q: How quickly do changes to permitted senders take effect?

A: Changes typically propagate within 30–60 minutes across your Office 365 environment.

Q: Is it possible to specify permitted senders for specific users only?

A: Yes. You can create transport rules in the Exchange Admin Center targeting specific users or groups.

Q: What happens if I permit a sender who later turns out to send spam?

A: You should promptly remove them from the Allow list and consider additional filters or rules to block unwanted messages.

Q: Do allow lists override all other spam checks?

A: Allowed senders bypass most spam filtering, but messages still undergo some security checks for malware or phishing indicators.