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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
62
Ranking in other categories
Email Archiving (1st), Email Security (2nd), Advanced Threat Protection (ATP) (2nd), Microsoft Security Suite (8th)
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 May 2026, in the Secure Email Gateway (SEG) category, the mindshare of Microsoft Defender for Office 365 is 17.0%, down from 29.5% compared to the previous year. The mindshare of Retarus Email Security is 1.0%, up from 0.2% compared to the previous year. It is calculated based on PeerSpot user engagement data.
Secure Email Gateway (SEG) Mindshare Distribution
ProductMindshare (%)
Microsoft Defender for Office 36517.0%
Retarus Email Security1.0%
Other82.0%
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

"It has helped us in improving our security posture; it detects any kind of attack or abnormal behavior in accessing the system and sends an alert to the administrator who can check, understand, and review on time to ensure that all activities are legit."
"My experience deploying Microsoft Defender for Office 365 was seamless."
"At the moment we are satisfied with this product. It's a stable, scalable, and resilient solution for us."
"Safe attachments, safe links, policies, and the ability to protect from zero-day threats are the most valuable features."
"Microsoft Defender for Office 365's most valuable features are safe attachments and safe links."
"The basic features are okay and I'm satisfied with the Defender."
"The most valuable feature of Microsoft Defender for Office 365 is data backups that we can provide through ticket requests."
"The email protection is excellent, especially in terms of anti-phishing policies."
"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

"The product must provide better malware detection."
"Microsoft sometimes has downtime, and we'll get several incidents coming in back to back. We have a huge backlog of notifications, many of which may be false positives. However, there might be serious alerts, so we can't risk dismissing all of them at once."
"In the areas of improvement for Microsoft Defender for Office 365, the console is the biggest challenge for me."
"There needs to be an improvement in integrating the product to work across multiple operating systems, and to have better support for non-Microsoft file types."
"The custom alerts have to improve a lot."
"The inbuilt analysis of false positives can be faster. It's not slow, but it can be faster."
"The only thing they should improve is the licensing model. They should stop changing it. A year ago, the five features I mentioned were included in one product. Now, three of them are bundled into one product, and you have to pay extra for the other two. I don't mind paying extra, but I don't want them to change it every year or every six months. I need to know what I'm looking at and not worry about it next year."
"The inbuilt analysis of false positives can be faster. It's not slow, but it can be faster."
"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

"It's a user-base subscription."
"The pricing has become expensive."
"The product is very expensive."
"While Microsoft Defender for Office 365 necessitates pricier E3 or E5 subscriptions, the extensive functionality offered by these licenses across various Microsoft products justifies the investment."
"It is much more expensive than using another solution because we have had to include some options and upgrade our license."
"Defender is a little bit more expensive as compared to others. We are in the manufacturing environment. So, we don't have a high budget for all of our endpoint devices. Its cost is a major concern for us."
"Microsoft Defender for Office 365 is an add-on to the Office license. Many customers are purchasing this solution."
"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
12%
Financial Services Firm
9%
Manufacturing Company
8%
Comms Service Provider
7%
No data available
 

Company Size

By reviewers
Large Enterprise
Midsize Enterprise
Small Business
By reviewers
Company SizeCount
Small Business24
Midsize Enterprise12
Large Enterprise32
No data available
 

Questions from the Community

What is your experience regarding pricing and costs for Microsoft Defender for Office 365?
My experience with pricing, setup, and licensing is that it's actually quite reasonable even on the licensing side as a standalone product. It's very competitive compared to what competitors are ch...
What needs improvement with Microsoft Defender for Office 365?
I think Microsoft Defender for Office 365 can be improved by creating more educational pieces about not just looking for malware. We are seeing a lot more malware-less emails that Defender for Offi...
What is your primary use case for Microsoft Defender for Office 365?
My main use cases for Microsoft Defender for Office 365 include email hygiene.
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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, Proofpoint, Mimecast and others in Secure Email Gateway (SEG). Updated: May 2026.
894,668 professionals have used our research since 2012.