collect-reminders: 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/sbin/collect-reminders - from package: email-reminder

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