title: SMTP email errors in Rails
body: <p>We just had our Rails app spit an error when ActionMailer was trying to send an email:</p>
  
  <p><code>Net::SMTPServerBusy - 451 Error while writing spool file</code></p>
  
  <p>We're using our own SMTP mailservers to send. Anyone know the details on this and how we can avoid it happening again in the future or if its possible to make ActionMailer try to send the email a few times if an error occurs?</p>
  
  <p>Thanks</p>