=?UTF-8?B?VHJ1ZUJsdWU=?= <jetblueairways@email.jetblue.com>

Encode::MIME::Header should do the trick:

>perl -MEncode=decode -MEncode::MIME::Header -E 'say decode("MIME-Head
+er", "=?UTF-8?B?VHJ1ZUJsdWU=?=")'
TrueBlue
>
[download]

Alexander