Further on the POP3 email checker

Well, since this project has been a bit of a surpirse hit, I thought I would include a few further notes and refinements.

This is a small change to the updateClient function that just flashes the LED rapidly four times to indicate the network is down:

void updateClient() //This function contacts the POP3 server
{
  if ((millis() - updateTimer) > 5000)
  {
    Ethernet.begin(mac, ip);
//    Serial.println("connecting...");
    delay(1000);
    if (client.connect())
    {
//    Serial.println("connected");
    client.println("user Pop.User"); //Insert your usual email login name
    client.println("pass YourPassword"); //And your password here
    client.println("quit");
    client.println();
    clientConnected = true;
    }
    else
    {
//    Serial.println("connection failed");
// Flash four time rapidly to indicate network down.
      for (int x = 0; x < 4; x++){
              digitalWrite(ledPin, HIGH); 
              delay(100);                
              digitalWrite(ledPin, LOW);  
              delay(100); 
      }
    }
    updateTimer = millis();
  }
}

What is odd is that when I have tried this with another LED it blinks very dimly - even when I move around which digital pin the other LED is coming from. Very odd and I still haven't figured out what is causing that.

Another thing to watch for is that this assumes that the number of emails comes through in array position 106 & 107 (I then subtract 48 to make the ASCII code into an integer):

          mailNum1 = inString[106] - 48; //Array position 106 contains the first digit
          mailNum2 = inString[107] - 48; //Array position 107 contains the 2nd digit if it is available

This, of course, may vary depending on how many characters there are in your POP3 server name and so on. I would recommend starting with the basic commands for getting the POP3 string back:

#include <Ethernet.h>

byte mac[] = { 0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED };
byte ip[] = { 192,168,0,172 };
byte server[] = { XXX, XXX, XXX, XXX }; // IP address of your POP3 server

Client client(server, 110);

long updateTimer;
boolean clientConnected = false;

void setup()
{
 Serial.begin(9600);
}

void loop()
{
 updateClient();
 checkAvail();
}

void updateClient()
{
 if ((millis() - updateTimer) > 10000)
 {
   Ethernet.begin(mac, ip);
   Serial.println("connecting...");
   delay(1000);
   if (client.connect())
   {
 Serial.println("connected");
 client.println("user user.name"); //Insert your usual email login name
 client.println("pass YourEmailPassword"); //And your password here
 client.println("quit");
 client.println();
 clientConnected = true;
   }
   else
   {
 Serial.println("connection failed");
   }
   updateTimer = millis();
 }
}

void checkAvail()
{
 if (clientConnected)
 {
   if (client.available())
   {
 char c = client.read();
 Serial.print(c);
   }
   if (!client.connected())
   {
 Serial.println();
 Serial.println("disconnecting.");
 client.stop();
 clientConnected = false;
   }
 }
}

Then watching the output in the serial window, which will look something like:

connecting...
connected
+OK hello from popgate 2.43 on pop108.xxx.xxx.xxx.xxx.xxx
+OK password required.
+OK maildrop ready, 0 messages (0 octets) (16335883)
+OK server signing off.

disconnecting.

You can then use this output to figure out the right position in the array for mailNum1 & mailNum2.

Hope that helps someone out there. It has been very flattering to see how many folks are interested in building this for themselves. As I explained in the first post, once you have the raw number of emails as an integer you can process with Arduino, you can do all sorts of interesting things beyond just flashing and LED!