Your copywriting should talk directly to your audience. For example, in subject lines, you can include the recipient’s city or address the email specifically with their name once they click to open. These details make your audience feel like you care about them specifically; not that you’re talking to thousands of people like they're all the same.
Knowing details about your audience is also a key component of copywriting. Do some audience research and make brand personas so you have an ideal person in mind that you’re writing to. These details can include gender, age, work, marriage, kids, what they care about. You can even make a fake name and use a stock photo so you can have a specific person in mind when you’re writing. This helps your copy feel more authentic.
The more you personalize content in email, the more your open and click rates will go up. Even with multiple audiences, make sure you’re not just personalizing their name, but the content as well. Architects, for example, have different pain points than contractors, so tailor that message to relate to each one separately.
On your blog, you can even write different articles for different audiences as long as you differentiate in some way, such as with a drop-down on the main blog page or a phrase in the title.