pmailq: 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/sbin/pmailq - from package: pmailq

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

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