in.imapproxyd: 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/in.imapproxyd - from package: up-imapproxy

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

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