title: smtplib sends blank message if the message contain certain characters
body: <p>My current script allows me to send emails fine, but there are just some characters it doesn't like, particularly <code>':'</code> in this sample.</p>
  
  <pre><code>import smtplib, sys
  
  mensaje = sys.argv[1]
  def mailto(toaddrs, msg):
      fromaddr = 'myemailblabla'
  
      username = 'thisismyemail'
      password = '122344'
  
      server = smtplib.SMTP('smtp.gmail.com:587')
      server.starttls()
      server.login(username, password)
      server.sendmail(fromaddr, toaddrs, msg)
      server.quit()
  
  mailto('test@gmail.com', mensaje)
  </code></pre>
  
  <p>If I write a sample message such as, let's say <code>"Hi there\n how are you?"</code> it works fine, but let's say I try to send a url <code>http://www.neopets.com</code>, the email is sent blank. I believe the <code>':'</code> causes this issue, so I tried escaping it, but nothing. </p>