opendmarc-check: 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/opendmarc-check - from package: opendmarc

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

On Debian possible default full paths are:

/usr/sbin/opendmarc-check - from package: opendmarc

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

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