send mails asynchronously in wcf

[jeevi]

Hello,

I am doing a wcf C#.net project in which i need to send multiple emails asynchronously with one pdf attachment. I use smtp.sendAsync() to do it. Please guide me on this and clarify my doubts.


The logic i have used is, store all the receiver's email ids in a list. Then, in a foreach loop, inside each loop call my function say, sendMailsaAsynch(objList, filename). This function is responsible for opening the pdf file using the filename specified, and attach it to a new object of MailAddress and call smtp.sendAsync().

function sendMailsAsynch(objList, filename)
{
//open the file
fs = new FileStream(...)           //LINE 1
mm = new MailMessage();
Attachment a = ....
.. smtp = new 
try
{
 smtp.SendCompleted += new SendCompletedEventHandler(smtp_OnCompleted);
 smtp.sendAsynch();
}
catch{ throw;}
finally { }
 
}

I want to delete the file in the finally. but i cannot access the file. Because, it says file is used by w3wp.exe. If i use mm.Dispose() in finally, none of the emails is sent. You may ask why i open the same file in every each loop in the LINE 1. But IF i do it in the calling function as shown below in the commented line, none of the emails are sent. I get Failure sending mail. some error like: Cannot access the mailaddress object. (Please explain where i can delete the file and how to delete it. I created the file using fs = new FileStream(filename, FileMode.Open, FileAccess.Read))


The following is how i call the function in foreach loop.

funcion sendMails(List list)
{
   //fs = new FileStream(....)
   foreach(List l in list)
   {
      sendMailsAsynch(list, filenme);
   }
}

One more important thing is: If i keep breakpoint and check in the smtp_OnCompleted delegate function, sometimes the breakpoint is hit after all the try-catch-finally is completed. ie. after all the loops are finished. But sometimes i get the breakpoint hit on this delegate function after the end of each try-cath ie. at the end for each loop. Can anyone explain how threading is handled here.

I do not want to use MessageQueing. I think it is not much of a complex issue. Hope someone will surely solve this. Thanks in advance.