Q:レガシーだからPEARをインストールして欲しい A:Composerでやれば簡単だよの件です。 ref: http://qiita.com/nntsugu@github/items/112b986af39774e3f5a8

composer.json

{
    "require": {
        "pear-pear.php.net/mail_mime" : "*",
        "pear-pear.php.net/http_request2" : "*",
        "pear-pear.php.net/mail_mimedecode" : "*"
    },
    "repositories": [
        {
            "type": "pear",
            "url": "http://pear.php.net"
        }
    ]
}