There will always be some content for your email marketing campaign that can be reused, recycled or repurposed. You do not have to reinvent the wheel every time you set out to communicate with your email marketing database. Recycling and repurposing your content can save you time and effort, because it is easier than creating everything originally every single time.
Sometimes, reusing content can be especially effective. If you had a certain offer that was very well received, then you may be able to revisit that offer again at a later date, hopefully with similar results. Or, reusing it for a separate or different segment of your email address database can also be very useful.
Keep track of which emails tend to get the best results. Then, repurpose that content and make it into something useful for another group of recipients, or offer it again to the same recipients (just be sure that the timing is good and that you are not being too redundant).
There are also times when you can take a whitepaper or newsletter and turn it into an email or even a post. You can use the same information for different purposes, when it is appropriate. Sharing your information through multiple channels can help you spread the word more effectively and get more exposure. Consider how you are trying to post your information on social media, while also on your blog. This is a great example of how information can be used in multiple ways to gain visibility and exposure.
Duplicate content is not what we are talking about, this is something frowned on. But, recycling and repurposing content is definitely a good idea in most cases. Reviews, testimonials and special offers make for the best reusable content, but keep track of what your recipients are most interested in and you will start to accumulate a bunch of great ideas that you can use again and again, only slightly altered, to increase your customer base and hopefully increase conversions.