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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)
2nd
Average Rating
8.4
Reviews Sentiment
6.8
Number of Reviews
61
Ranking in other categories
Email Archiving (1st), Email Security (2nd), Advanced Threat Protection (ATP) (3rd), Microsoft Security Suite (9th)
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 2026, in the Secure Email Gateway (SEG) category, the mindshare of Microsoft Defender for Office 365 is 14.8%, down from 28.2% compared to the previous year. The mindshare of Retarus Email Security is 1.1%, up from 0.3% 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 36514.8%
Retarus Email Security1.1%
Other84.1%
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 feature I like the most about Microsoft Defender for Office 365 is that it typically runs in the background—you do not know it is there until you need to access it."
"The ability to respond to threats if very important."
"Defender enables us to secure all 365-related activity from a single place. It gives us visibility into everything happening in Outlook, protecting us against phishing and other email-based threats. Defender helps us detect any suspicious behaviors."
"The most valuable feature of Microsoft Defender for Office 365 is the ease of use."
"It also gives the vulnerability status according to the versions you have selected. Let's say you have Google Chrome. It mentions the versions it has, and it updates. Within two hours of an update, it is reflected in the dashboard. That's really nice to have."
"The most valuable feature is protection against malicious links, fishing, and impersonation. You can train people to be aware of these threats, but they're not always careful. When they're using their phones between meetings, they click on a link, and it's game over."
"My experience with customer support and technical support for Microsoft Defender for Office 365 has been excellent."
"It also gives me good visibility because, with Defender, I'm using a Microsoft product to defend Microsoft products. The integration was really seamless and I have wide visibility because it picks up almost everything. Literally, I can see almost every activity that happens, from the e-mail to the workstation itself."
"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

"One area for improvement is support, in terms of being able to reach them and, especially, technical support for configuration."
"Sometimes I have to recategorize things when it takes the wrong step and I do not want it to classify something as suspicious."
"Microsoft wants its well-paying customers to finish testing some of its half-baked products, find bugs, and report bugs back to Microsoft's team, which is a little frustrating for those who have to manage it and roll it up to thousands of people across the organization."
"The GUI is sometimes slow to fetch the device report and could be improved."
"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."
"I'd like some additional features any product can give me to protect our environment in a better way."
"Configuration at the mid-level could be improved for the support team."
"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

"I was working in the government and it was too expensive for us to use our Microsoft products."
"I know that the product is incredibly expensive."
"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 is expensive. I typically recommend it only if clients have the budget. Otherwise, I would suggest an alternative."
"The product is expensive."
"Microsoft Defender for Office 365 comes with Microsoft Windows. It is free with the operating system."
"The solution could be better by simplifying the business model of their licensing. It was hard to figure out how to get the licensing done for the environment, initially."
"From the pricing point of view, like any other product in the market, there is scope for negotiation."
Information not available
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Top Industries

By visitors reading reviews
Computer Software Company
11%
Manufacturing Company
9%
Financial Services Firm
9%
Comms Service Provider
7%
No data available
 

Company Size

By reviewers
Large Enterprise
Midsize Enterprise
Small Business
By reviewers
Company SizeCount
Small Business24
Midsize Enterprise11
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
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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 Proofpoint, Microsoft, Mimecast and others in Secure Email Gateway (SEG). Updated: July 2026.
909,647 professionals have used our research since 2012.