C# File lock in Windows Service -

i wrote 1 windows service following.

1. call hand punch machine's vendor .exe generate text file data hand punch machine. store in temporary folder. .exe called using system.diagnostics.process.start

2. attach , send email file

   smtpclient client = new smtpclient();

   mailmessage mail = new mailmessage("f@abc.com", "t@abc.com");

   string[] fileentries = directory.getfiles(...);

   foreach (string filename in fileentries) { attachment attachment = new attachment(filename); mail.attachments.add(attachment);
   }

   client.send(mail);

3. move file temporary folder sent folder

i accomplish step 1 , 2, when try step 3 ( move file), file locked service ( sure not writing it).

how can move file?

smtpclient.send locking files. when used 'using', solved issue.