gmimeuuencode: 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/bin/gmimeuuencode - from package: gmime

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

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