Sure, let’s try these steps to make changes:
Open “MS Outlook” >> Click on “File” Tab >> “Account Settings” >> “Account Settings” >> Click on “Change” >> “More Settings” >> Move on “Outgoing Server” Tab >> Ensure the Option “My outgoing server (SMTP) require authentication” must be checked.
I got an informative article on the error 0x800ccc78.To get more info, see here: http://error.pstrecovery.net/outlook-error-0x800ccc78.html
I hope the information will be helpful in resolving your issue. Let me know if you need further assistance!!!