EntityFieldQuery causing column not found PDO exception
At a guess you're using the Email Field module to provide that particular field?

If so, the column name is email, not value, so your code should be:

$query-&gt;entityCondition('entity_type', 'node')
  -&gt;entityCondition('bundle', 'mail_entry')
  -&gt;fieldCondition('field_email', 'email', $email);