Recycle Bin is corrupted

Run Command prompt as Administrator.

rd /s /q C:\$Recycle.bin

This clears out the $Recycle.bin folder from the C:\ partition. You may have to do this for each hard disk partition in your system

Source: https://social.technet.microsoft.com

Remove duplicate lines with Notepad++

In replace dialog select "Regular expression" and ". matches newline"

Find what:^(.*?)$\s+?^(?=.*^\1$)
Replace with:

Source: https://stackoverflow.com

Remote desktop connection not working after CredSSP update

After Windows 10 1803 Cumulative update it's not allowed to connect with RDP to unpatched machines.
To disable security check - create DWORD AllowEncryptionOracle in registry:

HKLM\Software\Microsoft\Windows\CurrentVersion\Policies\System\CredSSP\Parameters\
Set AllowEncryptionOracle = 2

Be aware that disabling security check makes your machine vulnerable!

Source:  support.microsoft.com

Log off user from remote machine

Find user's session ID:
QWINSTA /SERVER:<hostname>

Log off user:
LOGOFF <sessionid> /SERVER:<hostname> /V

Send test email from PowerShell

Send-MailMessage -SMTPServer 192.168.0.1 -To to@email.com -From from@email.com -Subject "This is a test email" -Body "Hi, this is a test email"

Source: https://serverfault.com