My focus has always been when building a list the key metric is your open and click through rate. With that in mind many seem to wonder why they are not getting sales after getting 200 subs and start panicking because they hear stories of all these crazy open rates and $5k in income off of a list of 150 and all that and it throws them off.
But when you break it down the bottomline is nothing happens until something gets sold. Nothing gets sold if not enough people see your sales page. Not enough see the page if they dont click the link. Not enough click the link if they dont open the email. And the simple fact is that most WILL NOT open the email for various reasons, either your fault or theirs. which is why the industry standard is under 10%.
So the best way to counter act it is to make sure your subject lines are compelling with a clear call to action in the email if theres a link.
And dont panic until you see your open rate drop below industry standard and you have no sales after a significant amount of opens and clicks in the promo emails.
Oh and keep driving quality traffic.
That is my 2 cents. Feel free to chime in if you see it differently no problem.