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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) (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 June 2026, in the Secure Email Gateway (SEG) category, the mindshare of Microsoft Defender for Office 365 is 16.1%, down from 28.9% compared to the previous year. The mindshare of Retarus Email Security is 1.0%, 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 36516.1%
Retarus Email Security1.0%
Other82.9%
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 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."
"There are several features that I consider valuable."
"The deployment capability is a great feature."
"Our customers are satisfied with Defender for 365 because Microsoft products are easy to use and customize to meet the client's needs. Everything is in one place, so we can adjust policies as needed for phishing, DLP, ATP, or any other security features that our clients want to apply."
"The feature of Microsoft Defender for Office 365 that I like the most is probably the email features specifically, because those are the ones that a typical end user will accidentally click on a link not knowing what it is, and it'll catch it, and then it'll feed it over to Defender and stop the attack from happening before it actually can."
"Defender for Office 365 has helped eliminate having to look at multiple dashboards and that is the aspect I like most about it. It is simpler, effective, and convenient. The users like the process efficiency."
"It definitely is a must for email protection and O365 app DLP, and combined with Microsoft Defender for Endpoint, Microsoft Defender for Identity, and MCAS, it provides a holistic solution for threat protection, email protection, O365 apps protection, and DLP for both internal and external risks."
"We use Microsoft Defender for its ability to integrate with existing business technologies, which is beneficial for protecting business areas."
"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

"We are waiting for better software to block viruses."
"Configuring the default strategies and policies in Microsoft Defender for Cloud Apps generates a lot of noise and false positives."
"The changes to customer service, specifically the new model for support agreements, are not favorable."
"They can improve their security in a way where a customer can know if all their attachments are safe or not to open through a report. The solution does its job perfectly, but it never reports to the customer whether those attachments have been stopped before or not."
"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."
"Configuration requires going to a lot of places rather than just accessing one tab."
"The pre-sales cost calculations could be more transparent."
"The UI needs to be more user-friendly."
"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 pricing is normal. Considering its popularity, it's not overpriced."
"The product is very expensive."
"Compared to other brands, Microsoft Defender for Office 365's pricing is competitive."
"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."
"I know that the product is incredibly expensive."
"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 comes with Microsoft Windows. It is free with the operating system."
"It's a user-base subscription."
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Top Industries

By visitors reading reviews
Computer Software Company
12%
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
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 Proofpoint, Microsoft, Mimecast and others in Secure Email Gateway (SEG). Updated: June 2026.
900,747 professionals have used our research since 2012.