Overview
When opening an attachment (eg: PDF file) from an email in a public/shared folder, the attachment disappears and hence, the attachment cannot be read. The logs indicate that the attachment exists and the appropriate file size of the same is also shown in the logs.
Solution
This issue occurs on an older unsupported version of Kerio Connect (eg: Version 9.2.9 patch 1)
Upgrade the Kerio Connect server to the latest version to resolve this issue.