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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) (3rd), Microsoft Security Suite (9th)
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 August 2026, in the Secure Email Gateway (SEG) category, the mindshare of Microsoft Defender for Office 365 is 14.8%, down from 28.2% compared to the previous year. The mindshare of Retarus Email Security is 1.1%, 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 36514.8%
Retarus Email Security1.1%
Other84.1%
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

"Defender enables us to secure all 365-related activity from a single place. It gives us visibility into everything happening in Outlook, protecting us against phishing and other email-based threats. Defender helps us detect any suspicious behaviors."
"Since we have started using the solution, there have been fewer compromises."
"The most valuable feature of Microsoft Defender for Office 365 is the ease of use."
"One of the best features of the tool is its capability to aggregate insights from different workloads, basically from the Office 365 and endpoints part."
"I like its investigation capabilities, as that is what is most important to me. It is fairly simple with a user-friendly interface."
"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."
"It also gives me good visibility because, with Defender, I'm using a Microsoft product to defend Microsoft products. The integration was really seamless and I have wide visibility because it picks up almost everything. Literally, I can see almost every activity that happens, from the e-mail to the workstation itself."
"The technical support is good and quick to resolve issues."
"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

"From a development point of view, if I wanted to do development on my actual machine where Defender is, the organization can set certain policies or Defender makes that prohibitive."
"Sometimes, phishing emails manage to pass through the filter, so the system needs to enhance its phishing email detection capabilities."
"The custom alerts have to improve a lot."
"Microsoft Defender for Office 365 could improve by giving customers information on techniques to prevent threats."
"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?"
"I am generally satisfied with how it currently is. If I could improve anything, I would reduce the cost."
"In some situations, it has not been able to pick impersonated emails having no attachments. Technical support definitely has a scope for improvement."
"Specifically, within Microsoft Defender for Office 365, I want it to improve the DLP capabilities."
"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 product is very expensive."
"It is much more expensive than using another solution because we have had to include some options and upgrade our license."
"The product is expensive."
"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."
"The license is expensive because the cost is based on the number of users."
"Microsoft Defender is expensive. I typically recommend it only if clients have the budget. Otherwise, I would suggest an alternative."
"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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Top Industries

By visitors reading reviews
Computer Software Company
11%
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: July 2026.
908,834 professionals have used our research since 2012.