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Heimdal Email Security vs Microsoft Defender for Office 365 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

Cloudflare One
Sponsored
Ranking in Email Security
20th
Average Rating
8.6
Reviews Sentiment
6.5
Number of Reviews
23
Ranking in other categories
Secure Web Gateways (SWG) (12th), Data Loss Prevention (DLP) (21st), Cloud Access Security Brokers (CASB) (13th), Distributed Denial-of-Service (DDoS) Protection (8th), Software Defined WAN (SD-WAN) Solutions (12th), Access Management (11th), Bot Management (3rd), ZTNA as a Service (9th), ZTNA (4th), Secure Access Service Edge (SASE) (10th), Remote Browser Isolation (RBI) (3rd)
Heimdal Email Security
Ranking in Email Security
57th
Average Rating
9.0
Reviews Sentiment
7.9
Number of Reviews
1
Ranking in other categories
Fraud Detection and Prevention (57th)
Microsoft Defender for Offi...
Ranking in Email Security
2nd
Average Rating
8.4
Reviews Sentiment
6.8
Number of Reviews
61
Ranking in other categories
Email Archiving (1st), Advanced Threat Protection (ATP) (2nd), Microsoft Security Suite (8th), Secure Email Gateway (SEG) (2nd)
 

Mindshare comparison

As of June 2026, in the Email Security category, the mindshare of Cloudflare One is 1.6%, up from 1.6% compared to the previous year. The mindshare of Heimdal Email Security is 0.5%, up from 0.2% compared to the previous year. The mindshare of Microsoft Defender for Office 365 is 6.3%, down from 12.6% compared to the previous year. It is calculated based on PeerSpot user engagement data.
Email Security Mindshare Distribution
ProductMindshare (%)
Microsoft Defender for Office 3656.3%
Cloudflare One1.6%
Heimdal Email Security0.5%
Other91.6%
Email Security
 

Featured Reviews

CV
Network Architect at IP Dimension
Cloud security has improved remote access and has reduced costs for smaller client sites
I have used Cloudflare One's Identity-Aware Proxy, and it is quite straightforward from what I have seen so far. The app registration on the Azure side integrates fully into Cloudflare, and I am very satisfied with that part because it is easy to set up. The integration of Cloudflare One's Secure Web Gateway and Zero Trust Network Access works without any issues. That part is pretty automatic, and if you complete the rest of the setup, it comes together by itself with no issues from my side. What makes it nice is that we can actually start replacing on-site firewalls at this stage for the smaller clients because it does not matter if they go to a coffee shop or work from home; they are still secured by the same connection. The hops get shorter and you get better latency. We have done testing to see if it is better. One thing that we did notice with our proof of concept with our current client is that they have people connecting from the UK. When they used their previous VPN solution, uploading CAD drawings and other files to the server took a long time. They mentioned that it is much quicker on Cloudflare One's solution. I definitely believe that is part of the improved performance, and I am satisfied with that as well. What is nice about Cloudflare One is that it makes the setup easier and also easier to train technicians to maintain it. Compared to legacy systems, we do not need to get fancy firewalls in place that are costly. That is definitely also a cost-saver with Cloudflare One.
Melvin Ong - PeerSpot reviewer
Country Manager at PT Symcaw Solutions Indonesia
Straightforward to set up, reliable, and offers good functionality
We primarily use the solution for email security and general email management.  It's improved our productivity.  The solution works well overall. The functionality is very good.  The setup process is easy.  It is stable and reliable. It's scalable.  I don't have any specific areas that need…
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.

Quotes from Members

We asked business professionals to review the solutions they use. Here are some excerpts of what they said:
 

Pros

"Cloudflare is simple to use."
"Cloudflare Access is a stable solution."
"The simplicity of the solution is its valuable features as almost no effort was needed to learn the configurations. It is also one of the cheapest firewalls available in this category."
"The best feature is rate limiting. If I'm expecting 500 visits per hour, Cloudflare will limit the requests if I suddenly get 50,000."
"The capabilities of the software are strong enough for me to do what it's supposed to do. For me, we don't need to do a lot of configuration on our site. We just enable it and monitor it."
"Cloudflare, in my opinion, was easy to implement."
"Cloudflare DDoS is better than its competitors for its security, deployment, and scalability."
"It's a perfect solution from my perspective; it's easy to understand and easy to configure."
"It is stable and reliable."
"We have seen a return on investment because if we would have received a phishing email, Microsoft Defender for Office 365 would help out to detect the threat instead of crashing down the whole company."
"The email protection is excellent, especially in terms of anti-phishing policies."
"My experience deploying Microsoft Defender for Office 365 was seamless."
"We use Microsoft Defender for its ability to integrate with existing business technologies, which is beneficial for protecting business areas."
"The insights provided with Microsoft Defender for Office 365 are helpful because it comes with the E5 license, and by default, we can use a lot of capabilities."
"Some of the valuable features on the email side are anti-phishing, anti-malware, and Safe Links."
"It’s easy to handle integrations, and we don't need a lot of people in our IT team."
"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."
 

Cons

"When there are any dynamic changes in complex applications, the tool takes a lot of time, making its analytics-related area a major matter of concern where improvements are needed."
"The pricing is an area that can be improved. Pricing, as far as I recall, was the source of our problems."
"The free plan has limitations. For example, I can only set up three rules, and the application firewall is unavailable."
"The software has automated alerts, but the automated alerts are not available in the mobile app."
"Cloudflare One is not very powerful, but for what we require, it is basic and sufficient."
"For the topic of improvement, providing some training material is one of my suggestions."
"Cloudflare DDoS has poor technical support."
"Feedback could be enhanced. While I work efficiently with Clover as a partner in Mexico City, sometimes the information and requests are easier to manage with more concrete solutions."
"The solution could be less expensive."
"I am generally satisfied with how it currently is. If I could improve anything, I would reduce the cost."
"Its price should be improved. Its cost is a major concern for us."
"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."
"Microsoft Defender for Office 365 should improve the troubleshooting tools. It's unclear whether the device is blocked at the firewall level or at the device itself. The granularity needed for troubleshooting is currently lacking. From my perspective, Microsoft should address this issue to benefit many users who likely share the same sentiment."
"The visibility into threats is not up to the mark, as I do not have control. I rate my experience with Microsoft Defender for Office 365 as six out of ten due to troubleshooting and pricing concerns."
"The visibility for the weaknesses in the system and unauthorized access can be improved."
"There is a different console for different things; I just want one consolidated console."
"In one of the reports I can get the exact place where a vulnerable file resides. But for that, I need to explicitly go into the device and check. If they could include that file part in the report, without my having to go to the device itself, that would help."
 

Pricing and Cost Advice

"The solution is not that expensive."
"The solution's pricing lacks transparency."
"Cloudflare Zero Trust Platform's pricing is good."
"My company has to make yearly payments towards the licensing costs attached to the solution. There are no hidden charges apart from the licensing costs of the solution."
"The pricing of the solution is cheap. The licensing cost is also very low. I rate the cost and pricing a three out of ten."
"The prices are slightly expensive."
"The pricing is somewhere in the middle. I would rate the pricing a seven out of ten."
"The price tag is no longer $200,000, but rather $300,000 to $400,000. It's twice."
Information not available
"Microsoft Defender is expensive. I typically recommend it only if clients have the budget. Otherwise, I would suggest an alternative."
"It's a user-base subscription."
"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."
"For large enterprise organizations, they can definitely afford it, but for small and medium organizations, they might struggle to cover the expenses."
"The license is expensive because the cost is based on the number of users."
"The product is very expensive."
"Compared to other brands, Microsoft Defender for Office 365's pricing is competitive."
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Top Industries

By visitors reading reviews
Construction Company
19%
Comms Service Provider
10%
Financial Services Firm
9%
Manufacturing Company
8%
Construction Company
21%
Manufacturing Company
9%
Logistics Company
7%
Energy/Utilities Company
7%
Computer Software Company
12%
Manufacturing Company
9%
Financial Services Firm
9%
Comms Service Provider
7%
 

Company Size

By reviewers
Large Enterprise
Midsize Enterprise
Small Business
By reviewers
Company SizeCount
Small Business10
Midsize Enterprise1
Large Enterprise12
No data available
By reviewers
Company SizeCount
Small Business24
Midsize Enterprise11
Large Enterprise32
 

Questions from the Community

What needs improvement with Cloudflare Zero Trust Platform?
In my opinion, Cloudflare One can be improved mainly through compatibility, as the integration should be much simpler...
What is your primary use case for Cloudflare Zero Trust Platform?
Cloudflare One's primary use case for my organization is to protect servers and to provide remote access with the VPN...
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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...
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 ...
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.
 

Also Known As

Cloudflare Area 1 Email Security, Cloudflare Bot Management, Cloudflare Gateway, Cloudflare Zero Trust Platform, Cloudflare DDoS, Cloudflare SASE & SSE Platform
MailSentry
MS Defender for Office 365
 

Overview

 

Sample Customers

23andMe
Brother, Symbion, CPH West
Microsoft Defender for Office 365 is trusted by companies such as Ithaca College.
Find out what your peers are saying about Proofpoint, Microsoft, Check Point Software Technologies and others in Email Security. Updated: June 2026.
900,644 professionals have used our research since 2012.