title: c# Sending emails in threads using 1 connection
body: <p>I have a program for sending my resume to emails of people who posted jobs if they included their email in their post.</p>
  
  <p>so I send an email with their quote of the job description, date of when it was generated etc, </p>
  
  <p>so each email is unique, But each email uploads the same file (resume.pdf) as Attachment.</p>
  
  <p>right now each time I send an email I need to upload the same file (resume.pdf) // my resume</p>
  
  <p>so this are my questions: </p>
  
  <ol>
  <li><p>can I send each email and only upload my pdf resume once?</p></li>
  <li><p>right now I use a smtp client library like this: </p>
  
  <p><code>GMailSmtp gmail = new GMailSmtp(new NetworkCredential("username", "password"));</code></p></li>
  </ol>
  
  <p>so each time I send an email I create a thread that opens a new connection which seems time consuming to me.</p>
  
  <p>I was wondering if there is an API or library to create 1 connection and then send all the emails I want thru a queue or create a new thread just for sending the email.</p>