clamsmtpd: 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/clamsmtpd - from package: clamsmtp

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

On Debian possible default full paths are:

/usr/sbin/clamsmtpd - from package: clamsmtp

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

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