After Segmentation you are more likely to address the Exact Target Market you actually wanted to than before segmentation. Addressing the target market is more important on two counts – one you don’t want to address customers who are either not interested in this particular campaign or customers who are not likely to open or not likely to click on the links in your email, two you don’t want your deliverability to take a hit and hence losing your reputation as an email marketer.

Essentially your deliverability will improve, your reputation as an email marketer will improve, your conversions will improve if you make sure your emails are reaching those people who are more likely to be interested in the products that you are selling.