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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
6.8
Number of Reviews
60
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 February 2026, in the Secure Email Gateway (SEG) category, the mindshare of Microsoft Defender for Office 365 is 21.4%, down from 30.5% compared to the previous year. The mindshare of Retarus Email Security is 0.8%, up from 0.2% compared to the previous year. It is calculated based on PeerSpot user engagement data.
Secure Email Gateway (SEG) Market Share Distribution
ProductMarket Share (%)
Microsoft Defender for Office 36521.4%
Retarus Email Security0.8%
Other77.8%
Secure Email Gateway (SEG)
 

Featured Reviews

Emeka Ndulu - PeerSpot reviewer
Cloud Solutions Architect at a tech services company with 201-500 employees
Improves threat visibility and response while reducing manual tasks and training users against phishing
I appreciate the attack simulation feature whereby I get to train users and educate them on how to identify phishing emails and spam emails, as well as the anti-spam protection. It gives me visibility into my threat environment and threat landscape to ensure that I am one step ahead of any likelihood of threats within my environment. I get to detect it and respond, so the threat intelligence is very effective. Microsoft security solutions save my time. It saves money because once I protect my environment, I don't lose money. It has decreased my detection time and my time to respond.
WAKKAS AHMAD - PeerSpot reviewer
Security Consultant at Mahle
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

"The initial setup was easy."
"The ability to respond to threats if very important."
"Defender is a SaaS platform, so it offers more flexibility. Managing the permissions is easier. The solution's automated detection and response features are scalable."
"Defender helps us prioritize threats across our organization."
"Microsoft Defender for Office 365's most valuable features are safe attachments and safe links."
"It has significantly decreased my time to detection and response."
"Microsoft Defender for Office 365 saves me time; it does save a lot of time, especially with the automation."
"The most valuable feature of Microsoft Defender for Office 365 is its spam filter."
"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

"They have moved features from one console to another. Things have been moved around in the interface and it takes me time to find where certain features are."
"There's room for improvement regarding the time frame for retrieving emails."
"In one of the reports I can get the exact place where a vulnerable file resides. But for that, I need to explicitly go into the device and check. If they could include that file part in the report, without my having to go to the device itself, that would help."
"We are always looking for others tools to increase automation on tasks. There can be better integration with other solutions, such as PowerPoint and email."
"The phishing and spam filters could use some improvement."
"Microsoft should provide more documentation for users so they can self-educate. I would like to see more documentation for advanced security features."
"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."
"Microsoft Defender for Office 365 should improve the troubleshooting tools. It's unclear whether the device is blocked at the firewall level or at the device itself. The granularity needed for troubleshooting is currently lacking. From my perspective, Microsoft should address this issue to benefit many users who likely share the same sentiment."
"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 product is expensive."
"Defender for 365 comes in various plans and licenses, along with other Microsoft security solutions. Purchasing this kind of package or security bundle gives good value for money, and that's what I recommend."
"I know that the product is incredibly expensive."
"For licensing, it's usually a yearly package for customers who are subscribed to Office 365, but they can also pay on a monthly basis."
"The pricing has become expensive."
"The license is expensive because the cost is based on the number of users."
"For large enterprise organizations, they can definitely afford it, but for small and medium organizations, they might struggle to cover the expenses."
"I was working in the government and it was too expensive for us to use our Microsoft products."
Information not available
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Top Industries

By visitors reading reviews
Computer Software Company
13%
Financial Services Firm
8%
Manufacturing Company
8%
Comms Service Provider
6%
No data available
 

Company Size

By reviewers
Large Enterprise
Midsize Enterprise
Small Business
By reviewers
Company SizeCount
Small Business23
Midsize Enterprise10
Large Enterprise31
No data available
 

Questions from the Community

What needs improvement with Microsoft Defender for Office 365?
The inbuilt analysis of false positives can be faster. It's not slow, but it can be faster.
What is your primary use case for Microsoft Defender for Office 365?
My use case for Microsoft Defender for Office 365 is for email protection, safe links, protection of links, documents, protecting my documents, and protecting attachments. I also use it to conduct ...
Ask a question
Earn 20 points
 

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, Proofpoint, Abnormal AI and others in Secure Email Gateway (SEG). Updated: February 2026.
881,757 professionals have used our research since 2012.