No more typing reviews! Try our Samantha, our new voice AI agent.

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

"The most valuable feature of Microsoft Defender for Office 365 is its spam filter."
"Microsoft Defender for Office 365's most valuable feature is its performance."
"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."
"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."
"Defender helps us prioritize threats across our organization."
"It gives us visibility into threats and, for endpoints, it helps us to prioritize threats. We used to have a lack of visibility, but now our time to detect and respond has decreased."
"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 saves me time; it does save a lot of time, especially with the automation."
"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

"Microsoft security solutions work as expected. They are constantly updating the solutions to make them better. At the same time, the changes can impact a customer's environment, and we need to adjust settings. Sometimes we aren't aware of the changes, and nothing is pushed from the backend automatically."
"You should be able to deploy Defender for every subscription without the need to add servers."
"The GUI is sometimes slow to fetch the device report and could be improved."
"The UI needs to be more user-friendly."
"Specifically, within Microsoft Defender for Office 365, I want it to improve the DLP capabilities."
"I was looking for some advanced features, like if I would receive an email that contains a legitimate file type, but the content is malicious, how I can protect against that?"
"Sometimes I have to recategorize things when it takes the wrong step and I do not want it to classify something as suspicious."
"The visibility for the weaknesses in the system and unauthorized access can be improved."
"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."
"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."
"Microsoft Defender for Office 365 is an add-on to the Office license. Many customers are purchasing this solution."
"The license is expensive because the cost is based on the number of users."
"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."
"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."
Information not available
report
Use our free recommendation engine to learn which Secure Email Gateway (SEG) solutions are best for your needs.
900,747 professionals have used our research since 2012.
 

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.
Ask a question
Earn 20 points
 

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.