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Microsoft Defender for Office 365 vs Retarus Email Security comparison

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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 (2nd), Email Security (2nd), Advanced Threat Protection (ATP) (3rd), 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 November 2026, in the Secure Email Gateway (SEG) category, the mindshare of Microsoft Defender for Office 365 is 12.4%, down from 27.6% compared to the previous year. The mindshare of Retarus Email Security is 1.2%, up from 0.5% 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 36512.4%
Retarus Email Security1.2%
Other86.4%
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

"My experience deploying Microsoft Defender for Office 365 was seamless."
"The product's scalability is good."
"The coolest feature of Microsoft Defender for Office 365 is its ability to look for phishing emails."
"Microsoft Defender has a feature to protect each and every attachment. Even if it's an encrypted attachment, it will check for any potential threats."
"Microsoft Defender for Office 365's most valuable feature is its performance."
"The good part is that you don't have to configure it, which is very convenient."
"The two main features that prove most beneficial for us are URL scanning and attachment scanning."
"The stability of Microsoft Defender for Office 365 is fantastic."
"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

"Configuration requires going to a lot of places rather than just accessing one tab."
"The product must provide better malware detection."
"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."
"About eight months ago, we started to measure the quantity of phishing and spam that we have been receiving, and it has been increasing a lot. That means that protection for our email is not as good as we were expecting."
"One area for improvement is integration. For example, when it comes to external SaaS platforms, we were not able to get a lot of information on integrations with such apps for security and authentication."
"Microsoft Defender for Office 365 is not up to the mark in comparison with Wiz or Palo Alto."
"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."
"To improve Microsoft Defender for Office 365, it would be nice to have more accessibility for users to see on their end what they are doing that could cause a threat."
"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

"Compared to other brands, Microsoft Defender for Office 365's pricing is competitive."
"It is much more expensive than using another solution because we have had to include some options and upgrade our license."
"The license is expensive because the cost is based on the number of users."
"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 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."
"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."
"The pricing is normal. Considering its popularity, it's not overpriced."
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Top Industries

By visitors reading reviews
Computer Software Company
11%
Manufacturing Company
10%
Financial Services Firm
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 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: October 2026.
920,929 professionals have used our research since 2012.