reformail: 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 Debian possible default full paths are:

/usr/bin/reformail - from package: courier-maildrop
/usr/bin/reformail - from package: maildrop

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

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