Matt Mets’s Thing-a-Day projects are getting ridiculous:

Tonight’s project is a physical flag that attaches to my computer and goes up when I have new mail. First, I found biff, which is an extension to Thunderbird that proves a socket interface to poll for new mail status. Then, I wrote a little Python application to continuously poll the status and update the flag as necessary. Since I already had one written and didn’t feel like looking into any libraries, I used a C program to turn pins on the parallel port on and off to trigger the hardware. In a final bit of ridiculousness, I actually used some 555 timers to make an H-bridge to control the motor (don’t try that at home).

He released all the code and schematics. – Link.

Becky Stern

Becky Stern

Becky Stern ( is a DIY guru and director of wearable electronics at Adafruit. She publishes a new project video every week and hosts a live show on YouTube. Formerly Becky was Senior Video Producer for MAKE. Becky lives in Brooklyn, NY and belongs to art groups Free Art & Technology (“release early, often, and with rap music”) and Madagascar Institute (“fear is never boring”).

  • Niiice!

    I would prefer a blinking light… but a flag works too.


  • nickjohnson

    It’s a hardware biff.

    And believe it or not, I *have* used a 555 as a half H-bridge before ;)

  • jovino

    Funny, but in actuality the flag is supposed to be raised to indicate to the postman that you have outgoing mail waiting to be picked up. Shame that so many people get this wrong.

  • Richard

    I remember seeing a commercial product that retailed for some stupid amount back in the 90s that did this, it used the serial port and the software it came with was pretty brain dead in that it just checked your pop account for anything and raised its flag if there was anything in it.

    Still, a very good indication that something needs attention on your PC – could be used for outstanding comments for approval on a blog or whatever.

  • john


    blame AOL for making lots of people think that a red flag being up on a single mailbox means you have mail, they spread that wrong idea more then anyone.

    what you state about a flag being raised for outgoing mail is true for the box style for roadside delivery, that would be for individual boxes and a red flag. there are now also roadside delivery for streets/subdivisions that look just like apartment building/office mailboxes, just mounted outside and no flags (just stating that for completeness about roadside delivery, not that it adds much to the discussion).

    but to your point of indicating incoming mail, a number of manufacturers have made mechanical systems to show a flag (maybe yellow) when the box was opened (presumably by the postal carrier leaving mail). also there have been electromechanical and electrical and electronic add-on devices that can be purchased or made by a DIYer. So the idea of an incoming flag has long existed for the real life roadside boxes although not common and it wouldn’t be a red one.

  • mahto


    to jovino: Yeah, I realise that, but its not nearly as much fun that way. :-)

  • samf

    how about housing the mechanics in a small mailbox?
    cool project!