Hi Mark,

With Aweber not only you can track your open rates but even the links clicked.

I usually like spreading my followup emails within 3-4 days difference. It is suggested that first you send out the emails to the list that is most closely associated with the product and then to the other lists.

You can always change the body and subject when open rates are very low and then you can also save that list segment who did not open your email.

Hope this helps. Please let me know if you need any additional info.