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Microsoft Defender for Office 365 vs Retarus Email Security comparison

 

Comparison Buyer's Guide

Executive Summary

Review summaries and opinions

We asked business professionals to review the solutions they use. Here are some excerpts of what they said:
 

Categories and Ranking

Microsoft Defender for Offi...
Ranking in Secure Email Gateway (SEG)
1st
Average Rating
8.4
Reviews Sentiment
6.9
Number of Reviews
53
Ranking in other categories
Email Archiving (1st), Email Security (1st), Advanced Threat Protection (ATP) (2nd), Microsoft Security Suite (10th)
Retarus Email Security
Ranking in Secure Email Gateway (SEG)
16th
Average Rating
8.0
Reviews Sentiment
5.6
Number of Reviews
1
Ranking in other categories
No ranking in other categories
 

Mindshare comparison

As of August 2025, in the Secure Email Gateway (SEG) category, the mindshare of Microsoft Defender for Office 365 is 28.1%, down from 36.3% compared to the previous year. The mindshare of Retarus Email Security is 0.3%, up from 0.2% compared to the previous year. It is calculated based on PeerSpot user engagement data.
Secure Email Gateway (SEG)
 

Featured Reviews

Tolu Omolaja - PeerSpot reviewer
Great URL scanning and attachment scanning, but I would like more proactive threat analysis
The two main features that prove most beneficial for us are URL scanning and attachment scanning. URL scanning involves an automatic scan of links and emails. When a user clicks on a link within an email, the system promptly checks the link's safety. If the link is deemed safe, access is granted automatically. However, if it is flagged as unsafe, we receive feedback and notification to caution us about the potentially harmful link. At this point, we are presented with the option to proceed or return. I have personally witnessed the system identify a few unsafe links, making this the primary advantage of using the solution. The second crucial aspect is the scanning of attachments. When an email containing an attachment arrives, we receive a notification of the new email, along with information that the attachment is being scanned for threats. This additional layer of security provides peace of mind for our organization. While Microsoft Defender for Office 365 offers numerous features, these two stand out as particularly impressive and valuable to us.
WAKKAS AHMAD - PeerSpot reviewer
Provides valuable reports that make it easy to take action
Our primary use case for this solution is protecting emails This solution has helped our organization by protecting our emails from various threats. It helped us get customized reports on all of the emails we received on the user side and other data. The feature I found most valuable was getting…

Quotes from Members

We asked business professionals to review the solutions they use. Here are some excerpts of what they said:
 

Pros

"At the moment we are satisfied with this product. It's a stable, scalable, and resilient solution for us."
"The risk level notifications are most valuable. We get to know what kind of intrusion or attack is there, and we can fix a problem on time."
"Microsoft Defender for Office 365 helps people to work remotely. It is a secure solution. We don't need to use our company's computers or get VPN connections to the networks. I can control how they share screens and what they send to the devices. It keeps our organizations confidential and sensitive information safe."
"The two main features that prove most beneficial for us are URL scanning and attachment scanning."
"The benefit that stands out to me is the ability for multiple individuals to collaborate simultaneously within the same document. Additionally, there is the option to save the document directly in the integrated OneDrive or SharePoint."
"Microsoft Defender has a feature to protect each and every attachment. Even if it's an encrypted attachment, it will check for any potential threats."
"The most valuable feature of Microsoft Defender for Office 365 is data backups that we can provide through ticket requests."
"My experience with customer support and technical support for Microsoft Defender for Office 365 has been excellent."
"The feature I found most valuable was getting details on the emails, being alerted once those emails got a bad reputation, and then being able to take action on those emails."
 

Cons

"Too many false positives and lacks an accurate capability to detect malicious SharePoint sites."
"There is a different console for different things; I just want one consolidated console."
"It would be better if it were more scalable. It depends on the architecture, but we would like to make it more scalable for both data centers."
"We still see many false positives from time to time with Microsoft Defender for Office 365, so it would be good if we can reduce those false positives and provide better workflows for our end users, as sometimes they may not know what to do when they encounter a false positive."
"The product must provide better malware detection."
"The GUI is sometimes slow to fetch the device report and could be improved."
"The custom alerts have to improve a lot."
"I am generally satisfied with how it currently is. If I could improve anything, I would reduce the cost."
"This solution needs to improve the area of GUI as well as dashboards because they are very poor in terms of the current email security solution."
 

Pricing and Cost Advice

"The license is expensive because the cost is based on the number of users."
"The pricing has become expensive."
"The product is expensive."
"It's a user-base subscription."
"Microsoft Defender for Office 365 comes with Microsoft Windows. It is free with the operating system."
"The pricing is normal. Considering its popularity, it's not overpriced."
"Microsoft Defender for Office 365 is an add-on to the Office license. Many customers are purchasing this solution."
"I know that the product is incredibly expensive."
Information not available
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Top Industries

By visitors reading reviews
Computer Software Company
16%
Financial Services Firm
8%
Manufacturing Company
8%
Comms Service Provider
6%
No data available
 

Company Size

By reviewers
Large Enterprise
Midsize Enterprise
Small Business
No data available
 

Questions from the Community

What do you like most about Microsoft Defender for Office 365?
Threat Explorer is an invaluable tool for me, and it plays a crucial role in helping me discern the origins of various email campaigns, pinpointing where they emanate from, and identifying the indi...
What is your experience regarding pricing and costs for Microsoft Defender for Office 365?
Microsoft is quite affordable with a lot of features available for any size organization.
What needs improvement with Microsoft Defender for Office 365?
Microsoft could improve by offering recommendations for domain spoofing attacks, especially scenarios where DNS records like SPF, DKIM, and DMARC are not properly published. It's essential to enhan...
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Also Known As

MS Defender for Office 365
No data available
 

Overview

 

Sample Customers

Microsoft Defender for Office 365 is trusted by companies such as Ithaca College.
Information Not Available
Find out what your peers are saying about Microsoft, Abnormal Security, Proofpoint and others in Secure Email Gateway (SEG). Updated: August 2025.
865,295 professionals have used our research since 2012.