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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
7th
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
6.8
Number of Reviews
61
Ranking in other categories
Email Security (2nd), Advanced Threat Protection (ATP) (2nd), Microsoft Security Suite (9th), Secure Email Gateway (SEG) (1st)
 

Mindshare comparison

As of March 2026, in the Email Archiving category, the mindshare of KerioConnect is 2.2%, up from 0.8% compared to the previous year. The mindshare of Microsoft Defender for Office 365 is 19.7%, down from 35.2% compared to the previous year. It is calculated based on PeerSpot user engagement data.
Email Archiving Mindshare Distribution
ProductMindshare (%)
Microsoft Defender for Office 36519.7%
KerioConnect2.2%
Other78.1%
Email Archiving
 

Featured Reviews

MM
Senior Systems Tech/Admin at Samco Software Inc.
A seamless setup ensures smooth communication with comprehensive support
We remain a partner with Sophos and use XG S Firewalls without AWS implementation. We only use Sophos endpoint and Sophos Central. We host some clients on-premise while others we host remotely. The VPN connection is easy and proprietary, so it's not open to any other VPN clients. Communication with other mail servers is seamless. It can communicate with Gmail and Outlook without issues, provided the DNS settings are correct. We monitor our servers and security logs, implementing GeoIP blocking. We frequently block China and India IPs due to brute force attacks on our servers. We have extensive experience with KerioConnect. Backing up and maintaining it is straightforward compared to Microsoft Exchange, making it administrator-friendly. On a scale of 1-10, this solution rates an 8.
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

"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."
"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."
"This solution is our SMB alternative to Exchange, installed for more than forty SMB customers in a Linux environment with all of the collaboration features."
"It's relatively simple to use."
"The most valuable features are its ease of use, excellent pricing, and it is platform agnostic."
"We use the solution as a mail server. It connects with Outlook and is used for calendaring and similar tasks."
"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."
"We use Microsoft Defender for its ability to integrate with existing business technologies, which is beneficial for protecting business areas."
"It’s easy to handle integrations, and we don't need a lot of people in our IT team."
"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."
"The deployment capability is a great feature, and we're able to activate this feature throughout France with a click."
"The email protection is excellent, especially in terms of anti-phishing policies."
"The DLP feature of Microsoft Defender for Office 365 is valuable, and we also use the DLP feature for email real-time detection."
"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."
"Microsoft Defender for Office 365 has decreased my time to detection and time to respond by one hundred percent."
 

Cons

"This is just a cost, it's not something that's driving our business forward; it's just foundational."
"The solution could improve the redundancy because we only have one copy of the Kerio Connect server on our hardware."
"KerioConnect continues to improve with regular updates throughout the year. They must be added to the roadmap, which requires approval."
"Most of our clients use Outlook and Kerio Connect. Occasionally, Kerio can be a bit slow."
"I would like to see better support from their support team."
"Most of our clients use Outlook and Kerio Connect. Occasionally, Kerio can be a bit slow."
"I would like to see better support from their support team."
"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."
"We are always looking for other tools to increase automation on tasks. There can be better integration with other solutions, such as PowerPoint and email."
"The changes to customer service, specifically the new model for support agreements, are not favorable."
"I assess the stability and reliability of the solution as seven out of ten."
"The UI needs to be more user-friendly."
"We are always looking for others tools to increase automation on tasks. There can be better integration with other solutions, such as PowerPoint and email."
"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."
"It would be better if it were more scalable. It depends on the architecture, but we would like to make it more scalable for both data centers."
"I am generally satisfied with how it currently is. If I could improve anything, I would reduce the cost."
 

Pricing and Cost Advice

"KerioConnect has a first-time cost and yearly subscription. It is not expensive."
"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."
"The price of Kerio Connect is better when comparing it to others solutions."
"The pricing is about $3 per mailbox per month."
"It's a user-base subscription."
"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 was working in the government and it was too expensive for us to use our Microsoft products."
"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."
"The pricing is normal. Considering its popularity, it's not overpriced."
"I know that the product is incredibly expensive."
"Microsoft Defender is expensive. I typically recommend it only if clients have the budget. Otherwise, I would suggest an alternative."
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Top Industries

By visitors reading reviews
Comms Service Provider
13%
Manufacturing Company
10%
Computer Software Company
8%
Performing Arts
7%
Computer Software Company
13%
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 Business24
Midsize Enterprise10
Large Enterprise31
 

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?
The pricing is very easy to understand. As a partner, we have a monitoring system that informs us when subscriptions expire, allowing us to handle renewals. The pricing is very competitive.
What needs improvement with KerioConnect?
Since KerioConnect is a setup and go solution, everything works on its own. The only administrative tasks required are keeping it up to date, monitoring security logs, and ensuring protection from ...
What needs improvement with Microsoft Defender for Office 365?
The inbuilt analysis of false positives can be faster. It's not slow, but it can be faster.
What is your primary use case for Microsoft Defender for Office 365?
My use case for Microsoft Defender for Office 365 is for email protection, safe links, protection of links, documents, protecting my documents, and protecting attachments. I also use it to conduct ...
 

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: March 2026.
885,311 professionals have used our research since 2012.