Organizations wishing to operate their own mail servers have a number of different mail server platforms that they can choose between. Two of the leading platforms available today are Microsoft Exchange Server 2019 and Kerio Connect from GFI Software. This article examines the similarities and differences between these two platforms.

Organization Size

Microsoft Exchange Server can theoretically be used for any sized organization, although it is most often described as an enterprise grade mail platform. Microsoft does offer a Standard Edition of Exchange Server that is targeted toward non-enterprise class organizations, but its cost and complexity might be a deterrent to adoption by SMB class organizations.

Kerio Connect is specifically designed for the SMB market. It offers many of the same features as Exchange Server 2019, but tends to be easier to use. Perhaps more telling is the fact that Kerio Connect has a licensing plan that supports as few as ten users. The largest number of users covered by a Kerio Connect licensing plan (excluding GFI Unlimited plans) is 2999 users.


Pricing for Kerio Connect ( ranges from $29.50 per user to $36.50 per user, depending on the number of licenses purchased. There is an additional fee of $2 per user for the optional anti-spam extension. An antivirus extension is available for another $2 per user, and an ActiveSync extension is available for $3.50 per user. If an organization wants to purchase Kerio Connect and all of the available extensions, the price will range from $37 per user to $42 per user.

As an alternative, GFI offers a subscription-based plan called GFI Unlimited for $24 per user per month. This plan includes Kerio Connect and all of the extensions, as well as licenses to use all of GFI’s other software products.

Microsoft Exchange is available in either Standard Edition or Enterprise Edition. Either edition requires a license for each Exchange Server, and a Client Access License for each client. The Server license for Exchange Server 2019 Standard Edition is currently selling for $741.99, with the corresponding CALs selling for $97.99 for each user ( Exchange Server 2019 Enterprise Edition licenses sell for $4238.99, with the Enterprise CAL selling for $59.99 per user, in addition to the required Standard CAL ( Device CALs are available as an alternative to user CALs, but user CALs are typically less expensive given that users often work from multiple devices.

For those who prefer a cloud-based solution, access to Exchange Online is available through Microsoft Office 365 plans E1, E3, and E5. These plans range from $8.00 to $35.00 per user per month, and include access to other Office 365 software (

Time to Deploy

The amount of time required for deploying Exchange Server and Kerio Connect will vary from one organization to the next, based on things like IT expertise and the performance of the available computing hardware. Generally speaking, Kerio Connect can be installed and fully configured in less than an hour.

It can take a couple of hours to install Exchange Server, largely because of all of the prerequisite components that must also be installed. It is worth noting however, that Exchange Server usually requires extensive pre-deployment planning.

System Requirements

The Exchange Server system requirements vary by role ( Microsoft requires a 64-bit Intel or AMD processor, and recommends two physical processors if Exchange is being installed on a physical server. Microsoft also recommends a minimum of 128 GB of RAM for mailbox servers, and at least 256 GB of RAM for edge transport servers. Exchange Server 2019 supports up to 256 GB of RAM. Exchange Server also requires 30 GB of space, plus another 200 MB of space on the system drive, and 500 MB of space on the drive containing the message queue database. Additional space is required for the mailbox database.

Like Exchange Server, Kerio Connect’s hardware requirements vary based on the number of users that will be supported ( At a minimum, Kerio Connect requires a 64-bit CPU, 2 GB of RAM, and 40 GB of disk space. For Windows based machines supporting over 100 users, GFI recommends a quad core CPU running at 2.8 GHz or higher, 16 GB of RAM, and at least 200 GB of storage space.

Basic Capabilities

Both Kerio Connect and Exchange Server 2019 offer support for Email, calendars, contacts, and tasks, and both platforms provide very similar capabilities. For example, Kerio Connect and Exchange Server 2019 both allow for things like message filtering rules, shared calendars, delegation,  and free / busy assistance.

One significant difference between the two product’s basic feature sets is that Kerio Connect has native support for instant messaging. Microsoft also supports instant messaging, but does so through separate products such as Microsoft Teams or Skype for Business.

Administrative Capabilities

Kerio Connect and Microsoft Exchange include Web based administrative consoles. Kerio Connect utilizes the MyKerio console  to centralize the management of multiple Kerio Connect servers, however each Kerio Connect server includes its own built-in web management interface, while Exchange Server exposes similar capabilities through the Exchange Admin Center.

Not surprisingly, the Exchange Server and Kerio Connect management consoles are a lot alike. Both provide access to a variety of tools for managing user mailboxes, storage quotas, security settings, and much more.

One major difference between Exchange Server 2019 and Kerio Connect is that Microsoft provides an additional administrative tool called the Exchange Management Shell, a PowerShell-based command line environment. The Exchange Admin Center can be used for most of the day to day administrative tasks, but those wishing to make low level configuration changes must often use the command line to do so. The Exchange Management shell is also useful for scripting bulk changes to large numbers of mailboxes.


Microsoft Exchange Server is tightly integrated with the Microsoft Active Directory. Although the Exchange Admin Center does provide access to various security and compliance features, many aspects of Exchange mailbox security are implemented at the Active Directory level. The Exchange Admin Center exposes settings related to malware filtering, spam filtering, connection filtering, and domain keys (which are used for message authentication purposes). Exchange Server 2019 also includes numerous features related to auditing, eDiscovery, message retention, journaling, and auditing.

In Contrast, Kerio Connect does not require Active Directory integration, but does support it (along with other popular directories such as Apple Open Directory, Linux PAM, and a local user database). As such, Kerio Connect natively includes some basic mailbox level security features for the benefit of those who opt to use a local user database in place of the Active Directory or another directory system. For example, Kerio Connect includes a set of features that are meant to protect user passwords.

Like Exchange Server, Kerio Connect has support for domain keys (DKIM Signatures), and has built-in protection against directory harvesting attacks, and supports things like encrypted emails (S/MIME) and the remote wiping of mobile devices.

Both products offer an extensive collection of security features that go well beyond those that are listed in this article. Either platform should be able to keep your data secure, when properly configured. It is worth noting however, that because Exchange Server 2019 is a true enterprise class solution, it contains far more compliance related features than Kerio Connect does.


Although not completely identical to one another, Kerio Connect and Microsoft Exchange have feature sets that are very similar to one another. The primary differences between the two platforms are cost and scope. Kerio Connect is significantly less expensive than Microsoft Exchange, but is intended for use in SMB organizations. It also tends to be easier to configure and manage than Exchange Server. Conversely, Exchange Server costs more, but is well positioned for use in enterprise class organizations.

By: Brien M. Posey