mesg: 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/mesg - from package: sysvinit-tools

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

On Debian possible default full paths are:

/usr/bin/mesg - from package: orville-write
/usr/bin/mesg - from package: sysvinit-utils

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

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