For myself I liked the feature of tracking when the email is in the inbox of the user. Knowing that I can actually see when the recipient opened my email is pretty powerful. It is suitable for follow-up moves and measuring the response of recipients. Review collected by and hosted on G2.com.

Mailcastr only captures the opens in fluent within the Gmail. This is a major disadvantageous to me since I mainly deal with my clients and co-workers who are using other email service such as Outlook or Yahoo. Review collected by and hosted on G2.com.