svn-mailer: 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/svn-mailer - from package: svnmailer

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

On Debian possible default full paths are:

/usr/bin/svn-mailer - from package: svnmailer

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

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