You can check the following:
- Is the Subject line only written in CAPITAL letters?
- Does the subjectline contains "Best proposition", "Best offer", "Unique Offer", "10% discount", etc...
- Does your message have very little content?
- Does apparent links in the TEXT of your message start with « http:// » instead of this « www » ? (ex. : <a href=’http://www.mail.ru’>http://www.mail.ru</a> )
If you have answered "YES" to any of these questions, you must correct it and retry tests of deliveries.
If you have answered "NO" to all these questions, it's time to check if your IP isn't Blacklisted.