write-mime-multipart: command not found

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On CentOS possible default full paths are:

/usr/bin/write-mime-multipart - from package: cloud-utils

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/usr/bin/write-mime-multipart - from package: cloud-utils

You may install the required package with command apt-get install {package}

Error in other languages:
write-mime-multipart: bevel nie gevind nie
write-mime-multipart: comandă negăsită
write-mime-multipart: comando não encontrado
write-mime-multipart: commande introuvable
write-mime-multipart: command not found
write-mime-multipart: käsku ei ole
write-mime-multipart: không tìm thấy lệnh
write-mime-multipart: komanda nerasta
write-mime-multipart: Kommando nicht gefunden.
write-mime-multipart: kommandot finns inte
write-mime-multipart: komut yok
write-mime-multipart: nie znaleziono polecenia
write-mime-multipart: níor aimsíodh an t-ordú
write-mime-multipart: no se encontró la orden
write-mime-multipart: no s'ha trobat l'ordre
write-mime-multipart: opdracht niet gevonden
write-mime-multipart: parancs nem található
write-mime-multipart: perintah tidak ditemukan
write-mime-multipart: príkaz nenájdený
write-mime-multipart: příkaz nenalezen
write-mime-multipart: команда не найдена
write-mime-multipart: командата не е открита
write-mime-multipart: 命令找不到
write-mime-multipart: コマンドが見つかりません