maildirmake: command not found

Have You tried accessing the binary with the full path?

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

[root@server ~]# echo $PATH

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/maildirmake - from package: qmail
/var/lib/qmail/bin/maildirmake - from package: qmail

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