tex2mail: 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/tex2mail - from package: pari-gp

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

On Debian possible default full paths are:

/usr/bin/tex2mail - from package: pari-gp

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

Error in other languages:
tex2mail: bevel nie gevind nie
tex2mail: comandă negăsită
tex2mail: comando não encontrado
tex2mail: commande introuvable
tex2mail: command not found
tex2mail: käsku ei ole
tex2mail: không tìm thấy lệnh
tex2mail: komanda nerasta
tex2mail: Kommando nicht gefunden.
tex2mail: kommandot finns inte
tex2mail: komut yok
tex2mail: nie znaleziono polecenia
tex2mail: níor aimsíodh an t-ordú
tex2mail: no se encontró la orden
tex2mail: no s'ha trobat l'ordre
tex2mail: opdracht niet gevonden
tex2mail: parancs nem található
tex2mail: perintah tidak ditemukan
tex2mail: príkaz nenájdený
tex2mail: příkaz nenalezen
tex2mail: команда не найдена
tex2mail: командата не е открита
tex2mail: 命令找不到
tex2mail: コマンドが見つかりません