SwithMail can send silent emails, Send SMTP email silently from command line (CLI), or a batch file using Exchange, Gmail, Hotmail, or Yahoo! Plus. This program is very simple and easy to use, and it is open source.

Simple Usage:
1. Click "Configure Settings" to configure settings, it has 3 popular webmail clients settings built in;
2. Configure the settings for your SMTP server, enter From Name, username (usually full email address), and password;
3. Test your Settings, Click on the "Test Settings" button, and you will get a message box with either success or failure;
4. Save Settings and get your CLI string.

The license of this software is Free, you can free download and free use this email tool software.