Configure Thunderbird for localhost

 cf :  https://gist.github.com/raelgc/6031274

1. 帳號設定　->　新增其他帳號　->　Unix Mailspool(Movemail)(U)
2. 您的大名: chiao
3. 電子郵件地址: chiao@localhost
4. 寄件伺服器: localhost

As of Thunderbird 87beta.x.x, Movemail support is removed. 

https://www.thunderbird.net/en-US/thunderbird/87.0beta/releasenotes/