Mail_Mime is used to create MIME messages.Refer to the following command to install the Mail_Mime module.
root@[~]# pear install Mail_Mime
downloading Mail_Mime-1.8.3.tgz …
Starting to download Mail_Mime-1.8.3.tgz (30,929 bytes)
………done: 30,929 bytes
install ok: channel://pear.php.net/Mail_Mime-1.8.3
root@[~]# pear list | grep Mail_Mime
Mail_Mime 1.8.3 stable