r2e-migrate: 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

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 Debian possible default full paths are:

/usr/bin/r2e-migrate - from package: rss2email

You may install the required package with command apt-get install {package}
Error in other languages:
r2e-migrate: bevel nie gevind nie
r2e-migrate: comandă negăsită
r2e-migrate: comando não encontrado
r2e-migrate: commande introuvable
r2e-migrate: command not found
r2e-migrate: käsku ei ole
r2e-migrate: không tìm thấy lệnh
r2e-migrate: komanda nerasta
r2e-migrate: Kommando nicht gefunden.
r2e-migrate: kommandot finns inte
r2e-migrate: komut yok
r2e-migrate: nie znaleziono polecenia
r2e-migrate: níor aimsíodh an t-ordú
r2e-migrate: no se encontró la orden
r2e-migrate: no s'ha trobat l'ordre
r2e-migrate: opdracht niet gevonden
r2e-migrate: parancs nem található
r2e-migrate: perintah tidak ditemukan
r2e-migrate: príkaz nenájdený
r2e-migrate: příkaz nenalezen
r2e-migrate: команда не найдена
r2e-migrate: командата не е открита
r2e-migrate: 命令找不到
r2e-migrate: コマンドが見つかりません