Simple Mail Sender

local tArgs = { ... }
if #tArgs == 2 then
        if not tonumber(tArgs[2]) or not fs.exists(tArgs[1]) then
                print("Usage: " .. fs.getName(shell.getRunningProgram()) .. " <file_path> <receiverID>")
                return
        end
else
        print("Usage: " .. fs.getName(shell.getRunningProgram()) .. " <file_path> <receiverID>")
        return
end

local receiverID = tonumber(receiverID)
local filePath = tArgs[1]

function getFileContents(filePath)
        local file = fs.open(filePath, 'r')
        local fileContents = file.readAll()
        file.close()

        return fileContents
end

function getMessageTable(message)
        return {sender = os.getComputerID(), message = message}
end

function sendMessage(receiverID, mail)
        rednet.send(receiverID, textutils.serialize(mail))
end

sendMessage(receiverID, getMessageTable(getFileContents(filePath)))
print("Message sent.")