fmtcheck: 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/mu-mh/fmtcheck - from package: mailutils-mh

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

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