Fix Outlook not sending mail, but receiving with Kerio mail server
If you are receiving the 0x80048002 error during trying to send mail/mail getting stuck in outbox, and have installed the Kerio Outlook connector, check if the system wasn't previously using Office 2007 or Office 2010. If you don't know how if there was an older version of Office installed, check these following folders if it contains
%CommonProgramFiles%\System\MSMAPI on 32bit Windows or with 64bit Outlook 2013/2016/365
%CommonProgramFiles(x86)%\System\MSMAPI on 64bit Windows WITH 32bit Outlook 2013/2016/365
If this is the case, fully uninstall Kerio Outlook Connector and fully clean your system from previous versions of Office. Even if you copy the KoF DLLs into the specific folders, Kerio connector will fail during an update and you'll end up with the same problem. You can paste the DLL files into the MSMAPI folder temporalily to test if that is the cause of the problem.