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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
61
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

"One of our clients didn't have the budget to invest in a SOC team, but we deployed the solution for them, and they now run a SOC with only one analyst."
"The most valuable feature of Microsoft Defender for Office 365 is data backups that we can provide through ticket requests."
"The deployment capability is a great feature, and we're able to activate this feature throughout France with a click."
"The insights provided with Microsoft Defender for Office 365 are helpful because it comes with the E5 license, and by default, we can use a lot of capabilities."
"My experience deploying Microsoft Defender for Office 365 was seamless."
"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."
"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."
"Microsoft Defender for Office 365 is a stable solution."
"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

"This is quite an expensive solution and understanding the pricing model and features is quite complicated and it can, in fact, be a nightmare when dealing with Microsoft."
"I am generally satisfied with how it currently is. If I could improve anything, I would reduce the cost."
"The UI needs to be more user-friendly."
"There needs to be an improvement in having the product work across multiple operating systems and have better support for non-Microsoft file types."
"The product must provide better malware detection."
"The custom alerts have to improve a lot."
"The phishing and spam filters could use some improvement."
"Sometimes I have to recategorize things when it takes the wrong step and I do not want it to classify something as suspicious."
"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

"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."
"Microsoft Defender for Office 365 is an add-on to the Office license. Many customers are purchasing this solution."
"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."
"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."
"The pricing has become expensive."
"The pricing is normal. Considering its popularity, it's not overpriced."
"I know that the product is incredibly expensive."
Information not available
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893,244 professionals have used our research since 2012.
 

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 Business25
Midsize Enterprise12
Large Enterprise31
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.
893,244 professionals have used our research since 2012.