"The days that emails were filtered based on content only are long gone. In the war against growing volumes of spam and fraudulent email such as phishing, ISPs and incoming spam filters are continuously using more and more techniques to filter the bad guys from the good guys. Since email is critical for most businesses, getting email into the inbox is valuable. Deliverability is not only an issue for bulk email, such as newsletters and smart campaigns, but also (and maybe even more important) for transactional email like order confirmations. In fact, it is an issue for all outbound emails"

Read the full post here: Email marketing and deliverability: an interview with Reputy.