- mb_encode_mimeheader: documentation ( source)
<?php
/*
mb_internal_encoding('ISO-8859-1');
echo 'Subject: ', mb_decode_mimeheader('=?ISO-8859-1?B?0JTQvtCx0LDQstC70LXQvSDQvdC+0LLRi9C5INC60L4=?=
=?ISO-8859-1?B?0LzQvNC10L3RgtCw0YDQuNC5INC6INC30LDQv9C40YHQuDogIns=?=
=?ISO-8859-1?B?UEFHRV9USVRMRX0i?=');
*/
$name = 'Добавлен новый комментарий к записи: "{PAGE_TITLE}"';
$addr = mb_encode_mimeheader($name, "ISO-8859-1", "B");
echo $addr;