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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
8th
Average Rating
6.8
Reviews Sentiment
7.1
Number of Reviews
10
Ranking in other categories
Email Applications (10th)
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 August 2025, in the Email Archiving category, the mindshare of KerioConnect is 1.6%, down from 2.8% compared to the previous year. The mindshare of Microsoft Defender for Office 365 is 31.9%, up from 15.7% compared to the previous year. It is calculated based on PeerSpot user engagement data.
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

"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."
"It's relatively simple to use."
"The user interface is good."
"KerioConnect has integration with 365. We can use Outlook, which has its client and can be used with Apple devices. It integrates with the App Store and Microsoft Office. It has a smart router. The spam filtering and antivirus are good."
"We use the solution as a mail server. It connects with Outlook and is used for calendaring and similar tasks."
"We have contacted technical support a handful of times and received some assistance."
"The most valuable features are its ease of use, excellent pricing, and it is platform agnostic."
"The most valuable features are security and privacy because you installed it on your server, within your company premises, not in the cloud."
"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."
"Microsoft Defender for Office 365 has improved my organization's security. It makes it easier to manage the infrastructure without the help of third-party applications."
"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."
"We use Microsoft Defender for its ability to integrate with existing business technologies, which is beneficial for protecting business areas."
"The most valuable feature of Microsoft Defender for Office 365 is data backups that we can provide through ticket requests."
"The most valuable feature is the integration. It's a single console, so we don't have to switch around between multiple products. Another valuable feature is the ease of operations and maintenance."
"The ability to respond to threats if very important."
"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."
 

Cons

"It could be simpler to use and install, but I still wouldn't use it because there isn't a compelling use case."
"I would like to see better support from their support team."
"Having a native Outlook map integration would make Kerio Connect better."
"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"
"Most of our clients use Outlook and Kerio Connect. Occasionally, Kerio can be a bit slow. They could make it faster to get onto the web interface without so much load time. It's just slow with Outlook, however, for some reason."
"KerioConnect continues to improve with regular updates throughout the year. They must be added to the roadmap, which requires approval."
"The search and archiving documentation capabilities need to be stronger."
"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."
"There's room for improvement regarding the time frame for retrieving emails."
"They can improve their security in a way where a customer can know if all their attachments are safe or not to open through a report. The solution does its job perfectly, but it never reports to the customer whether those attachments have been stopped before or not."
"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 changes to customer service, specifically the new model for support agreements, are not favorable."
"Microsoft Defender for Office 365 could improve by giving customers information on techniques to prevent threats. For example, information about best practices on how to protect their own devices against hackers and scammers, such as educational information or training. This would help others have a better understanding of cyber security. Additionally, there can be more security features added."
"One area for improvement is support, in terms of being able to reach them and, especially, technical support for configuration."
"Specifically, within Microsoft Defender for Office 365, I want it to improve the DLP capabilities."
 

Pricing and Cost Advice

"The price of Kerio Connect is better when comparing it to others solutions."
"KerioConnect has a first-time cost and yearly subscription. It is not expensive."
"The pricing is about $3 per mailbox per month."
"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."
"Microsoft Defender for Office 365 comes with Microsoft Windows. It is free with the operating system."
"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."
"I know that the product is incredibly expensive."
"For licensing, it's usually a yearly package for customers who are subscribed to Office 365, but they can also pay on a monthly basis."
"Microsoft Defender is expensive. I typically recommend it only if clients have the budget. Otherwise, I would suggest an alternative."
"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."
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Top Industries

By visitors reading reviews
Computer Software Company
14%
Comms Service Provider
11%
Manufacturing Company
8%
Retailer
6%
Computer Software Company
16%
Financial Services Firm
8%
Manufacturing Company
8%
Comms Service Provider
6%
 

Company Size

By reviewers
Large Enterprise
Midsize Enterprise
Small Business
 

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?
Microsoft could improve by offering recommendations for domain spoofing attacks, especially scenarios where DNS records like SPF, DKIM, and DMARC are not properly published. It's essential to enhan...
 

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: July 2025.
865,384 professionals have used our research since 2012.