We host our site on Amazon EC2. Our users subscribe for weekly email alerts. Since many IPs with EC2 are with a history, to make sure mails are not marked as spam, we use a third party SMTP service. Recently, Amazon has also set up reverse DNS entry for us. We haven't received any abuse notice so far.
I receive couple of these emails on my personal gmail account and those are not marked as spam. How do I know if any of our emails are being marked as spam?