How to create a personalised email based on specific client data

How can I send a personalised business email (newsletter) based on a specific metric of customer data?

We need to send personalised promotional material to our customers who live in specific postcodes.
Should we use Excel, mail merge, VBA, code?

For example, we have 100 clients, in 20 postcodes, 100 separate products that are only relevant to clients who live in the postcode of the product.

Instead of sending 100 products to 100 clients, we only want to send them the 20 that are in their same postcode.

So the logic is:
If client is in post code x, they receive a list of all the products that are in postcode x.

Hope this makes sense.

Welcome to the forum.
You can go with Mail merge, easy to set it up for your requirement.

Please provide some sample data in excel I'll give you the Mail merge in word.