SYMPTOMS
After manual SmarterMail webmail configuration in IIS, Plesk displays the following warning on
Plesk, Server, Component Management page:
Notice: Undefined index: smartermail in
C:\Programme\SWsoft\Plesk\admin\plib\class.DefPackageMng.php on line 378
CAUSE
Most likely the reason of the problem is that SmarterMail website in IIS has got Host Header values specified.
RESOLUTION
Please go to
IIS, Web Sites, SmarterMail Website, Properties, Web Site, Advanced and remove host header values keeping SmarterMail listening to all connections on all IPs on port 9998