Decode Mail Subject

reformime is in maildrop package

reformime -h "header"
Decode a MIME-encoded "header" and print the decoded 8-bit content on standard output.

e.g.
# reformime -h '=?big5?B?Rnc6ILt+t3ykaqRGISAtLS0+sd+kVzEwOjMwq+G5cbZPrNmr3KZottw/?='
Fw: 誤會大了! --->晚上10:30後電費省很多嗎?