local mail_spam = function(playername, param)
    local number = tonumber(param)
    if not number then
        number = 10
    end
    for i = 0, number do
        local success, err = mail.send({
                from = "singleplayer",
                to = playername,
                cc = "",
                bcc = "",
                subject = string.format("subject line %04d", i),
                body = "mail body test test"
        })
    end
end


minetest.register_chatcommand("mail_spam", {
    params = "",
    description = "Spam a mailbox of user with mails",
    privs = { server = true },
    func = mail_spam
})