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KerioConnect vs Microsoft Defender for Office 365 comparison

 

Comparison Buyer's Guide

Executive SummaryUpdated on Jun 29, 2025

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

KerioConnect
Ranking in Email Archiving
6th
Average Rating
7.2
Reviews Sentiment
7.3
Number of Reviews
11
Ranking in other categories
Email Applications (9th)
Microsoft Defender for Offi...
Ranking in Email Archiving
1st
Average Rating
8.4
Reviews Sentiment
6.9
Number of Reviews
53
Ranking in other categories
Email Security (1st), Advanced Threat Protection (ATP) (2nd), Microsoft Security Suite (10th), Secure Email Gateway (SEG) (1st)
 

Mindshare comparison

As of October 2025, in the Email Archiving category, the mindshare of KerioConnect is 1.9%, down from 2.6% compared to the previous year. The mindshare of Microsoft Defender for Office 365 is 26.8%, up from 18.4% compared to the previous year. It is calculated based on PeerSpot user engagement data.
Email Archiving Market Share Distribution
ProductMarket Share (%)
Microsoft Defender for Office 36526.8%
KerioConnect1.9%
Other71.3%
Email Archiving
 

Featured Reviews

David Bloomer - PeerSpot reviewer
Lightweight, simple, and robust; easy to maintain and doesn't require a lot of system resources to run
Kerio Connect does as advertised, so there are no real issues with the product itself. It's developed regularly, so there are constant updates. Possibly, the support and development have lessened since they've sold the company, but as far as the product itself is concerned, there isn't anything that I would suggest needs improvement. If I'm being picky, Kerio Connect uses a proprietary, mappy atom for Outlook, and it would be nice if they used a native mappy connection instead, but that's the only additional feature that I would like to see in its next release. If they have native Outlook map integration, that would be great, but other than that, it's got all the functions that I think a mail server should have.
Tolu Omolaja - PeerSpot reviewer
Great URL scanning and attachment scanning, but I would like more proactive threat analysis
The two main features that prove most beneficial for us are URL scanning and attachment scanning. URL scanning involves an automatic scan of links and emails. When a user clicks on a link within an email, the system promptly checks the link's safety. If the link is deemed safe, access is granted automatically. However, if it is flagged as unsafe, we receive feedback and notification to caution us about the potentially harmful link. At this point, we are presented with the option to proceed or return. I have personally witnessed the system identify a few unsafe links, making this the primary advantage of using the solution. The second crucial aspect is the scanning of attachments. When an email containing an attachment arrives, we receive a notification of the new email, along with information that the attachment is being scanned for threats. This additional layer of security provides peace of mind for our organization. While Microsoft Defender for Office 365 offers numerous features, these two stand out as particularly impressive and valuable to us.

Quotes from Members

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

Pros

"What I like most about Kerio Connect is that it supports ActiveSync, and that is its most critical feature. The solution is also a nice, simple, robust, and stable mail server."
"Backing up and maintaining it is straightforward compared to Microsoft Exchange, making it administrator-friendly."
"We have contacted technical support a handful of times and received some assistance."
"The most valuable features are security and privacy because you installed it on your server, within your company premises, not in the cloud."
"The solution is easy to maintain, unlike Exchange. It's easy to create multiple domains and back up and restore if needed. It also has good security features like anti-spam and antivirus."
"We use the solution as a mail server. It connects with Outlook and is used for calendaring and similar tasks."
"It's relatively simple to use."
"The user interface is good."
"Defender for 365 is a comprehensive cloud-based solution. The value of the cloud is that you aren't alone. Threat intelligence and analytics are shared in the cloud. We don't have to find the solution alone. If you face an unknown threat with traditional solutions like Trend Micro and Symantec, you need to open a case and send your information to them to analyze forensically and identify the source of the attack."
"Defender for Office 365 has helped eliminate having to look at multiple dashboards and that is the aspect I like most about it. It is simpler, effective, and convenient. The users like the process efficiency."
"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."
"The product is not resource-intensive."
"The two main features that prove most beneficial for us are URL scanning and attachment scanning."
"The DLP feature of Microsoft Defender for Office 365 is valuable, and we also use the DLP feature for email real-time detection."
"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."
"Scalability-wise, I do not think there are any issues so far."
 

Cons

"We are considering switching to Microsoft Exchange. One reason is that it doesn't improve our workflow and doesn't integrate well with Microsoft 365 applications."
"KerioConnect is stable as long as you use a strong password."
"You cannot integrate with other services like Google Docs, Google Assistant, Google Calendar, etc."
"The solution could improve the redundancy because we only have one copy of the Kerio Connect server on our hardware. The next step for us is to move to the cloud and if Kerio does not have a cloud version available they should release one"
"It could be simpler to use and install, but I still wouldn't use it because there isn't a compelling use case."
"The search and archiving documentation capabilities need to be stronger."
"Having a native Outlook map integration would make Kerio Connect better."
"KerioConnect continues to improve with regular updates throughout the year. They must be added to the roadmap, which requires approval."
"Sometimes, phishing emails manage to pass through the filter, so the system needs to enhance its phishing email detection capabilities."
"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."
"You should be able to deploy Defender for every subscription without the need to add servers."
"One area for improvement is support, in terms of being able to reach them and, especially, technical support for configuration."
"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."
"We noticed that from time to time, Microsoft's stability does have problems. Sometimes the service goes up and down. Sometimes they change without prior notice."
"Specifically, within Microsoft Defender for Office 365, I want it to improve the DLP capabilities."
"The XDR dashboard has room for improvement."
 

Pricing and Cost Advice

"KerioConnect has a first-time cost and yearly subscription. It is not expensive."
"The pricing is about $3 per mailbox per month."
"The price of Kerio Connect is better when comparing it to others solutions."
"The solution's pricing depends on how long you plan to keep it because you pay on a per-year basis. You might have a one-time setup cost for something like Microsoft Exchange or a Linux mail server. I'd say this solution is expensive on a per-year basis, almost 2000-3000 dollars annually. It doesn't seem to pay off yet, so we're considering switching to another product."
"Compared to other brands, Microsoft Defender for Office 365's pricing is competitive."
"The product is expensive."
"The pricing has become expensive."
"The product is very expensive."
"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 pricing is normal. Considering its popularity, it's not overpriced."
"It is much more expensive than using another solution because we have had to include some options and upgrade our license."
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Top Industries

By visitors reading reviews
Comms Service Provider
12%
Computer Software Company
12%
Manufacturing Company
9%
Retailer
7%
Computer Software Company
15%
Financial Services Firm
8%
Manufacturing Company
8%
Comms Service Provider
6%
 

Company Size

By reviewers
Large Enterprise
Midsize Enterprise
Small Business
By reviewers
Company SizeCount
Small Business10
Midsize Enterprise2
By reviewers
Company SizeCount
Small Business23
Midsize Enterprise8
Large Enterprise27
 

Questions from the Community

What do you like most about KerioConnect?
The most valuable features are security and privacy because you installed it on your server, within your company premises, not in the cloud.
What is your experience regarding pricing and costs for KerioConnect?
KerioConnect has a first-time cost and yearly subscription. It is not expensive.
What needs improvement with KerioConnect?
KerioConnect continues to improve with regular updates throughout the year. They must be added to the roadmap, which requires approval. In larger organizations, the server's capabilities and the da...
What do you like most about Microsoft Defender for Office 365?
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 indi...
What is your experience regarding pricing and costs for Microsoft Defender for Office 365?
Microsoft is quite affordable with a lot of features available for any size organization.
What needs improvement with Microsoft Defender for Office 365?
I think that Microsoft Defender for Office 365 could be improved if it could use VirusTotal to compare the programs or anything that I download. VirusTotal helps to identify viruses, malware, troja...
 

Also Known As

No data available
MS Defender for Office 365
 

Overview

 

Sample Customers

Southern Tier Brewing Company, Innotta, Baustoff + Metall, Hamifleurs, Chanson TV, Ryman Stationery
Microsoft Defender for Office 365 is trusted by companies such as Ithaca College.
Find out what your peers are saying about KerioConnect vs. Microsoft Defender for Office 365 and other solutions. Updated: September 2025.
869,202 professionals have used our research since 2012.