title: How to troubleshoot MC emails not delivering to active subscribers
body: <p>Sometimes I feel like I don't understand Salesforce at all.</p>
  <p>My company uses Salesforce and Marketing Cloud. I'm the one who sends emails in MC, but I'm having trouble investigating the cause of some undelivered emails. We have a handful of Salesforce campaigns created specifically to hold contacts for a series of mass emails. I added the Salesforce campaigns to the audience list when sending the latest email. After accounting for duplicates and contacts without email addresses, there were approximately <strong>40,000</strong> that would receive the email. But only <strong>32,000</strong> actually sent.</p>
  <p>Some of these email addresses were unsubscribed, but many were marked as Active or not in the All Subscribers list in Marketing Cloud. I've looked through the reports and can't seem to find one that looks like it would shed some light on this issue. And the Salesforce Help site is not helpful.</p>
  <p><em><strong>Why would active subscribers not receive emails? Can I even send emails to someone who is opted into email in Salesforce but who's not in the All Subscribers list in Marketing Cloud?</strong></em></p>