Overview

Your users report that Kerio Outlook Connector (KOC) search function has become slow, causing Outlook to stop responding, freezing, or hanging. Performing entire mailbox search actions can load slowly and cause Kerio Outlook Connector Offline Edition and Outlook crashes. You have concerns about the Synchronization Performance you see with KOFF.

Solution

When reviewing KOFF Performance issues, this is most often related to the system resources, mailbox size, or configuration options in use on the end-user PC. Generally speaking, synchronization, opening, and searching large mail folders are the most common activities where these performance troubles appear. 

Common Environmental Factors

As a first step, review the following common environmental factors that can adversely impact the overall performance of Kerio Outlook Connector.

1. Kerio Connect or KOFF is Outdated
   1. The Development Team is continually working to address identified performance-related defects. As such, it is suggested that you ensure that your Kerio Connect server is up-to-date.
   2. Depending on your KOFF Update Policy (WebAdmin > Configuration > Advanced Options > Software Updates), your users may not be automatically updated with the server and may be running an older release.
2. Limited End-user PC hardware specs
   1. It is recommended that the computer have at least 4 GB of RAM.
   2. It is suggested that the PC utilize an SSD to run KOFF smoothly.
      1. Note: Network Attached Storage(NAS) is not recommended for storing the KOFF cache.
3. Mailbox Exceeds the Recommended Size
   1.  With Outlook 2019, Outlook 2016, Outlook 2013, and Outlook 2010, the maximum number of folders is 500.
   2. We suggest keeping mailboxes under 20GB total size and less than 10,000 items in each folder.
      1. If there are folders with over 10,000 items, please split those folders into smaller subfolders.
      2. To help manage user mailbox sizes, you can explore Archiving Older Emails, Automatic Cleanup, or Limiting the size of user mailboxes.
4. KOFF Directories have not been excluded from Antivirus Scans
   1. As KOFF is periodically modifying the user's PC folders, it is advisable to exclude the following folders from the local Antivirus software check:
      • C:\Program Files\Kerio\Outlook Connector (Offline Edition)
      • C:\Program Files (x86)\Kerio\UpdaterService
      • C:\Users\<username>\AppData\Local\Kerio\Outlook Connector

High Impact Outlook Settings

If you continue to see trouble after addressing the above environmental issues, this may indicate problems with Outlook itself that require troubleshooting. You can explore Repairing Outlook as a first step. If the trouble persists, consider disabling the following high-impact Outlook settings:

1. Disable 'Group by' View and Outlook Instant Search
   1. In Outlook 2003 and above, there is an option to show emails in groups. If you find that folders (such as the Sent Items) take an excessive time to load, it is recommended to disable the 'Group by' view, which is the view option Show in groups.
   2. In Outlook 2007, the instant search option can cause slowness in Outlook with KOFF. KOFF has its built-in searching and does not depend on the Outlook Instant Search feature. We have noticed significant improvements after disabling the Outlook instant search feature. 
2. Disable High-Impact Filtering Rules
   1. Filter rules that move items to non-standard folders may cause reduced or sluggish responsiveness.
   2. Follow Filtering and Sorting Messages in Outlook to double-check the settings.
3. Disable Other Plugins
   1. Other MAPI or antivirus plugins may conflict with the Kerio Outlook Connector, resulting in slow load times or message downloads.
   2. If none of the options above works, it is recommended to temporarily disable any other Outlook plugins to identify if there is a conflict causing the degraded performance:
      1. In particular, make sure to disable Outlook integration with Microsoft Skype for Business as it uses Free/Busy status synchronization.
      2. If the performance does not improve after disabling the plugins, please contact Kerio support to report the issue.

Testing

After addressing any identified environmental issues, repairing the Outlook installation, and disabling high-impact Outlook settings, the performance within KOFF is improved, and users can search and synchronize content without encountering hangs or crashes.