Download emails (backup) from gmail programmatically

Question

Does anyone know a way to execute a bulk dump of every email of a gmail account and write the emails to a file?

I'm looking to write a program that would let users back up there gmail (probably via imap) and back it up to either individual files or as a pst (I know pst will probably be much harder)

Answer 1

some time ago I wrote a blog post about exactly same topic. See HOWTO: Download emails from a GMail account in C# for details.

Code uses our Rebex Mail component:

using Rebex.Mail;
using Rebex.Net;
...
// create the POP3 client
Pop3 client = new Pop3();
try
{

   // Connect securely using explicit SSL. 
   // Use the third argument to specify additional SSL parameters. 
   Console.WriteLine("Connecting to the POP3 server...");
   client.Connect("pop.gmail.com", 995, null, Pop3Security.Implicit);

   // login and password
   client.Login(email, password);

   // get the number of messages
   Console.WriteLine("{0} messages found.", client.GetMessageCount());

   // -----------------
   // list messages
   // -----------------

   // list all messages
   ListPop3MessagesFast(client); // unique IDs and size only   
   //ListPop3MessagesFullHeaders(client); // full headers
}
finally
{
   // leave the server alone
   client.Disconnect();      
}


public static void ListPop3MessagesFast(Pop3 client)
{
   Console.WriteLine("Fetching message list...");

   // let's download only what we can get fast
   Pop3MessageCollection messages = 
      client.GetMessageList(Pop3ListFields.Fast);

   // display basic info about each message
   Console.WriteLine("UID | Sequence number | Length");
   foreach (Pop3MessageInfo messageInfo in messages)
   {
      // display header info
      Console.WriteLine
      (
         "{0} | {1} | {2} ",
         messageInfo.UniqueId,
         messageInfo.SequenceNumber,
         messageInfo.Length
      );

      // or download the whole message
      MailMessage mailMessage = client.GetMailMessage(messageInfo.SequenceNumber);
   }   
}