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Kerio 6.5 review

This is an older review. Current versions extend these features.

I first reviewed Kerio Mailserver in 2003. A lot has changed since then, so I thought it might be time to go through the features.

Note: I am a reseller of this product, so this isn't an unbiased review. However, I'm selling KMS because I like the product - it's not the other way around. Also, keep in mind that I'm a tech guy, not a sales guy: if you want to call me up and chat about your specific needs and concerns, that's fine. I like to talk tech and if you end up wanting a quote, that's great. If not, I'm not going to pester you with a dozen emails and voice mails, because tech guys don't do that, right? Right.


Kerio Mailserver can run on Windows (Vista, 2003 SP1, XP SP1, XP SP2, 2000 SP4), Mac OS X (10.3, 10.4, 10.5) and 32 bit Linux (Red Hat Enterprise Linux 3 / 4 / 5, Fedora Core 5 requires compat-gcc-32-3.2.3-56.fc5 and compat-libstdc++-33-3.2.3-56.fc5 packages, Fedora Core 6, 7, and 8 Requires: libstdc++.so.5 SUSE Linux 10.0, 10.1, 10.2, and 10.3 Requires: libstdc++.so.5). I personally prefer to run it on Linux, especially for large numbers of users.

Note that you can also install this as a pre-installed VMware Virtual Appliance in VMware Player or VMware Workstation or VMware ESX Server.

XML files and indexes

One of the things I really like about Kerio is that its configuration files are XML based. That means that when push comes to shove, you can fix things with a plain old text editor.

It also keeps mail messages in separate files as plain text and builds index files from them. That gives both great flexibility (see Automatically cleaning Kerio Mail Folders for an example) and provider robustness: if somehow an index is damaged, you simply stop the mailserver, rename the offending "index.fld" as "index.bad" and restart the server. It will rebuild indexes upon first access.

Kerio Outlook Connector and Offline Connector

The Kerio Outlook connector is a free plug-in for Microsoft Outlook 2007 , Microsoft Outlook 2003 (SP2) and Microsoft Outlook XP (SP3). It provides the most full-featured experience for mail - you CAN simply use Pop or Imap, but KOC (or KOFF for traveling users) is what you want for Calendaring, Free/busy scheduling and public folders (these features are also available with the webmail client).

Kerio Webmail

This is a very versatile webmail - two versions can be used. The full featured version supports all features and drag and drop functionality, while the low-bandwidth version is ideal for poor or low speed connections.


No plugins or optional software are required for Microsoft Entourage. Just point it at the Kerio server and go.

Mobile Email

Kerio is constantly adding more support for mobile devices.

Optional McAfee Virus scanning

This scans incoming and outgoing mail. This does NOT install McAfee on any client machines and does not protect the server OS: it just scans emails. It's very inexpensive and I really recommend using this version.

You can also add a second scanner. For example, see Using ClamAV on Mac.

Open Directory and Active Directory

If you have Active Directory or Open Directory, you can pull user authentication directly from your directory server - no duplication of work when adding and removing employees.

Archiving and Backup

Kerio mail server can track every single piece of mail in and out of your organization and store a copy of it safely away. Optionally, you can enable deleted message recovery for your users.

Spam filtering

Kerio offers multi-level spam filtering, starting when another server first connects to your server. Read about all the spam fighting tools here.

Note: spam filtering is a constantly moving target. That's one reason why keeping your Kerio server up to date with the latest version is very important.

Although a GUI panel provides the ability to write custom spam rules, you can also write directly in the underlying Sieve language for even more control.

Real Mailing Lists

Kero has a real mail list processor built in. Stop maintaining mail lists in Excel spreadsheets: Kerio Mail Server Mailing Lists.


The free administration client can be installed on Linux, Mac or Windows regardless of what OS your server runs on. As mentioned above, the config files it accesses are easily understandable XML files.

There's also a web based admin panel that provides less features - it only allows administration of user accounts. This lets you spread out some simple admin tasks.

I know there's more that you might like to know about. If you are within an hour or so drive, I'm happy to come out and help you install a 30 day demo at your business (demos can be extended if you need more time to test). If you are cross country, we can do it by phone and even remote access.

Tony Lawrence 2008-04-12 Rating: 4.5

Kerio MailServer ,Internet Mailserver ,Exchange Replacement ,Kerio Mailserver 6

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© Anthony Lawrence

Sat Sep 20 06:40:41 2008: 4584   Vishant

can u please help me in configuring the mail server to keep a copy of outgoing and incoming mails under a different email address. i.e any mails coming inside or going outside the organisations should be sent to one id assigned so that they can be tracked.

please help me. i m not able to do this in this current version.


Sat Sep 20 11:17:48 2008: 4585   TonyLawrence

All current versions of Kerio can archive to an email address. That's usually used for compliance with SOX and the like

Archiving and Backup -> Archive to remote email address

Mon Sep 22 20:50:45 2008: 4590   Vishant

hi again,
thanks for your reply it solved my problem. thanks a lot.

i have one more issue and that is--- is it possible that we can assign some users the email accounts only on which they can send the mails and not to others? where as for the rest it should work normally.

i have seen this kind of thing in mdaemon mail server.

is it possible to allot two smtp relay servers to kerio for two different mail domains?


Mon Sep 22 20:56:36 2008: 4591   TonyLawrence

If I understand you correctly, the setting you want is on the last User configuration panel "This user can send/receive to/from his/her own domain only".

SMTP delivery is server wide, not per domain.

Tue Sep 23 03:14:07 2008: 4592   Vishant


no this is not the thing that i want. i don't want the user to be able to send the mails to his/her domain only. but he/she should be only allowed to send the mails to the email addressess that i specify wheather of his/her domain or an external domain he/she should be allowed to send mails to some particular email addressess only.

Tue Sep 23 10:43:12 2008: 4593   TonyLawrence

No, there is no such ability within Kerio.

Thu Nov 27 23:16:18 2008: 4824   Vishant

hi Again,

ur help earlier in mail server really helped me a lot. today i have another problem but this time in firewall. i want to block all kind of chats in kerio but i m just not able to do it. google chat stops in the website but google talk will just not get blocked can u please help me create some rules to do that.

please provide me ur direct contact information also.


Thu Nov 27 23:54:07 2008: 4825   TonyLawrence

I don't know what port or ports Google chat uses, sorry. If you Google for "block Google chat" I'm sure you can find all the help you need.

Direct contact info is listed under the "Help" link but please be aware that I do not offer free help by email or phone unless you are purchasing Kerio through me. See (link) for more information.

Kerio Connect Mailserver

Kerio Samepage

Kerio Control Firewall

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