the SMTP protocol is ASCII based. In the past, the SMTP protocol goes unencrypted over the wire means you can simply send email by connecting to the SMTP port 25 and enter some SMTP commands via telnet:
michael@debdev ~ # telnet smtp.yourdomain.org 25
This is a test message. End with <ENTER><ENTER> and point
some usefull tools like telnet.exe are disabled by default in Windows Vista and later version. You can enable this and other features by command line using dism.
dism called with the get-features parameter lists all available features and its current state.
Note: Featurenames are case sensitive.
C:\>dism /online /Get-Features
Feature Name : TelnetServer
State : Disabled
Feature Name : TelnetClient
State : Enabled
and the Enable-Feature option install them