Recently we had to create a application which sends out more than 50000 mails each week.
 I have tried building these type of application in ASP, PHP, Coldfusion and a minor attempt with ASP.NET.

 ASP and PHP ... It was a nightmare... Every week there was a new problem with the Application... I had to conclude that ASP and PHP was not build to handle this amount of server operations.
 Coldfusion-- Im pretty happy with the out put found here. They have got a gud spooling technique suitable for Mass mailing. Also I was able to use their event gateway technology to send mass mails in no time. It was really greate.

 Now in ASP.NET.. When I send it in a one process, It is sending much better than any other language (Don't know about java and Perl).
  But still it takes time if there are 50000 mails and each send after extracting the address from the DB. And often it gets timed out.
 So I tried to use threading... Was almost near to my ideal Mass Mailer App.. But when started sending more than 10000 mails it showed some errors (System memory overflow)...

 Im now confused on which way to go..
 I need a application which will complete the browser operations in seconds and say "50000 mails have been kept for processing. A mail will be send to you when the system completes sending all the mails".

 Does this makes any sense.

 I would like some experts gathering here to talk on this.
 And like always gud technologies and ideas will come out from better thinking and communication.:D