lmtpd: command not found

Have You tried accessing the binary with the full path?

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/lib/cyrus/bin/lmtpd - from package: cyrus-common

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