How to Whitelist a Domain in Office 365?

Published On - April 19, 2024 by Prakriti | Reading Time: 5 minutes

Filtering spam or threat/ suspicious emails is a must-do task for security concerns. The same applies to Exchange Online, which deliberately filters and diverts emails to junk/ spam folders. However, protection from malware and phishing attempts has a positive side from security points, but it still creates an issue in some scenarios.

The problem starts when your legitimate and important emails start falling into the junk or spam folder, and you need to whitelist a domain in Office 365.

No one wants to miss important emails, as they can negatively affect professional work. Whitelisting is an effective step to eliminate this issue and ensure that no important emails fall into the Junk or Spam Folder. You can either whitelist a domain or an online website service or IP address, too. However, we will focus the way to whitelist a domain in Office 365.

Why There is A Need to Whitelist a Domain in Office 365?

  • If Microsoft’s Exchange Online Protection feature, using a score-based algorithm, diverts emails from important senders to a spam folder or junk folder, then there is a need to whitelist.
  • A domain needs to be whitelisted in Office 365 to ensure that regular clients’ or partner emails do not become spam or junk and are available in real-time.
  • For large organizations that have sub-organizations using multiple domains, ensuring uninterrupted email communication whitelisting is a must.

Ways to Whitelist a Domain in Office 365

There are a few ways to get rid of essential emails in Office 365, but it is recommended that you whitelist a domain in Office 365 using Mail Flow Rules. This is the most secure way to Whitelist a domain without compromising security.

Using Mail Flow Rules to Whitelist a Domain in Exchange Online

  1. First, go to the Exchange Admin Centre.
  2. Now, expand the mail flow and click on Rules.Open Exchange Online to Whitelist
  3. Here, click on the add sign, and from the many options, select the Bypass spam filtering.
  4. Set the rule conditions, such as name, description, and exception, like the other settings that are asked to be set.
  5. Choose “Apply this rule if” >> “The Sender”. Whitelist Exchange Online Domain
  6. Domain is>> dropdown. Enter the domain name and specify the domain for which you want to bypass Exchange Online Protection.
  7. Now, click on the add (+) to add other conditions. Select an IP address that is in any of these ranges or exactly matches and enter the IP address that you want to bypass. Whitelist domain
  8. Subject or Body >> Includes Any of These Words in Subject (to bypass an email containing the given words).
  9. A message header >> includes any of these words. You must filter the DMARC results to prevent the spoofing of whitelisted domains. Under “Enter Text,” add Authentication results, and in the same way, “dmarc=pass” under enter words.
  10. Finally, set rule setting and review. Click on the Finish. Apply Rule and Finish

Whitelist a Domain in Office 365 Using Microsoft 365 Defender

With this, we will update the default anti-spam inbound policy.

  • First, open the Microsoft 365 Defender Portal.
  • Under Email and Collaborations, select Policies & rules>> Threat Policies>> Anti-spam policies (it may take a few minutes to load the policies). Whitelist a domain in Office 365
  • Scroll down and click Edit allowed and blocked senders and domains.
  • Now, click on Allow domains.
  • Here, add the domains that you want to whitelist.
  • Finally, save the setting when it’s done.
  • So, this is how one can Whitelist a domain in Office 365.

Are There Any Preventive Steps that Professionals Take for Office 365 Emails?

We all know how important emails are for any professional, and no one wishes to compromise the security of Office 365 emails. Moreover, to manage Office 365’s storage/ subscription plans wisely, Office 365 email backup is trending as a necessity.

Free Download100% Secure Buy NowPrice: $89

By having a copy of Office 365 emails in local storage, users can prevent any unwanted scenarios, such as unknowingly deleting emails or experiencing any unexpected glitch. To back up Office 365 emails efficiently and effortlessly, Regain Office 365 Email Backup Tool is a one-stop solution. Let’s know what does it offer:

  • There are no limitations on the number and size of Office 365 mailboxes.
  • Moreover, it works for Exchange On-Premises; it is best suited if your organization is running a hybrid environment.
  • Users get multiple prominent file formats to save/back up Office 365 emails, such as Office 365 to PST, MBOX, MSG, and EML/EMLX.
  • It comes with a simple and user-friendly GUI; any user can back up Office 365 emails on their own.
  • Users can also select/ remove the folders before starting the backup. It shows a preview of the Office 365 mailbox.

Wrapping Up:

To ensure that no email from the most important sender falls into the spam folder/junk, the process of whitelisting a domain in Office 365 is prevalent. In this write-up, I have explained two ways to whitelist a domain in Office 365. Moreover, for business and professional needs, a backup of Office 365 emails is suggested. To back up Office 365 emails, Regain Office 365 Email Backup Tool is the picture-perfect utility. You can also try its free demo version to explore its features.


Frequently Asked Questions:

Ques 1. What credentials do I need to Whitelist a domain in Office 365?

Ans. You need Admin credentials to Whitelist a domain in Office 365. Only an Admin Can Whitelist a domain to bypass security checks and receive an email in the inbox.

Ques 2. With the Office 365 email backup tool described in the blog, what options do we have to open the backup file format?

Ans. The software offers multiple file formats for backup, and accessing and opening backups depends on the file format. If you have taken a backup in PST file format, then you can use Outlook to add and open the PST file. Moreover, for the MBOX file format, Thunderbird and other email clients are the options.

Ques 3. If I need help backing up Office 365 emails, whom should I contact?

Ans. If you need any assistance backing up Office 365 emails using the Regain Office 365 Email Backup Tool, feel free to contact our technical support team. Our team is available 24/7. You can contact us using live chat or telephone or write to

Ques 4. What is the best method to Allow a domain in Exchange Online to bypass spam filtering?

Ans. The most secure way is using Mail Flow. We can also bypass the security checks through Microsoft Defender, but it is not secure; it includes a risk of fishing and malware attacks.

Author: Prakriti

Hi, I am Prakriti (Pooja), a dedicated technology enthusiast and writer, focusing on the realm of email and its related technologies. Working closely with Regain Software, I delve into the intricate aspects of email protocols, email clients, servers, and other related dimensions. Through insightful articles, I aim to demystify complex concepts into understandable write-ups for a wide audience.

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