Resolution
This error means that the web site ‘webmail (default)’, responsible for webmail is not configured correctly in IIS. The following commands need to be launched to fix the problem:"%plesk_bin%\websrvmng.exe" --reconfigure-webmail
"%plesk_bin%\defpackagemng.exe" --fix --type=webmail.horde Note: wbemail.horde value is taked by default. In case of using another webmail engine it is necessary to check one under the following registry key :
HKLM\ SOFTWARE\Plesk\PSA Config\Config\Packages\webmail