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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

"Since we have started using the solution, there have been fewer compromises."
"It’s easy to handle integrations, and we don't need a lot of people in our IT team."
"The features I appreciate most about Microsoft Defender for Office 365 are admin notifications for potential threats along with protecting our Microsoft apps such as Outlook from potential phishing attacks."
"The stability of Microsoft Defender for Office 365 is fantastic."
"Threat Explorer is an invaluable tool for me, and it plays a crucial role in helping me discern the origins of various email campaigns, pinpointing where they emanate from, and identifying the individuals within our organization who are affected."
"Safe attachments, safe links, policies, and the ability to protect from zero-day threats are the most valuable features."
"Does a thorough job of examining email and URLs for malicious content."
"Microsoft Defender for Office 365 helps people to work remotely. It is a secure solution. We don't need to use our company's computers or get VPN connections to the networks. I can control how they share screens and what they send to the devices. It keeps our organizations confidential and sensitive information safe."
"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

"In some situations, it has not been able to pick impersonated emails having no attachments. Technical support definitely has a scope for improvement."
"The phishing and spam filters could use some improvement."
"The inbuilt analysis of false positives can be faster. It's not slow, but it can be faster."
"Microsoft Defender for Office 365 must improve the overall management style, including the GUI. It also needs to change the filters so that it is easy to whitelist and blacklist data."
"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."
"We need a separate license and we don't know how to get the license that is required."
"They have moved features from one console to another. Things have been moved around in the interface and it takes me time to find where certain features are."
"We are always looking for others tools to increase automation on tasks. There can be better integration with other solutions, such as PowerPoint and email."
"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

"From the pricing point of view, like any other product in the market, there is scope for negotiation."
"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."
"It's a user-base subscription."
"For large enterprise organizations, they can definitely afford it, but for small and medium organizations, they might struggle to cover the expenses."
"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."
"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 license is expensive because the cost is based on the number of users."
"Compared to other brands, Microsoft Defender for Office 365's pricing is competitive."
Information not available
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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.
902,495 professionals have used our research since 2012.