Insert text from records where wanted in other text?

I have customer’s name, email, and phone number. I have thousands of records. I want to automatically generate a letter for all these customers, and want to include these three text records in that letter.

Is there any way to insert those records automatically throughout the text?

For example, into this template (just example not actual):

Hello [Name],

We tried to reach you at your phone number [Phone Number] and blah blah blah.

I have a text template and want to insert the records throughout it.