exiqgrep: 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/sbin/exiqgrep - from package: exim

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

On Debian possible default full paths are:

/usr/sbin/exiqgrep - from package: exim4-base

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

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