On the Persuasive e-Marketing blog, Kelly Rusk explains why you should take a strategic approach to email marketing, rather than a tactical one to achieve the best results with your program.
You are taking the strategic approach if you have a content plan, an editorial calendar, a mailing schedule, a segmentation strategy. You research who your audience is and give them what they want. Your email plan revolves around other company marketing initiatives. You carefully examine results and constantly work to improve. When needed, you consult experts and stay up-to-date on industry best practices.
You are taking a tactical approach if you fire out emails to your list. Your content for each email is hastily planned just before sending. Although the finished product may look professional and complete, behind the scenes is a fury of disorganization and chaos. You occasionally look at results, but don't analyze.
It's obvious why the strategic approach is the way to go :-)
Read Kelly's post here, she provides a great example of her own on how you can slip from a strategic approach to a tactical.