imapsync: 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 CentOS possible default full paths are:

/usr/bin/imapsync - from package: imapsync

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