How to extract contacts informations from emails

Hello, I've been using an email account for professional use and I would like to gather all the contacts (email address and names) I got from the past 2 years (to start a newsletter).

The webmail of my email provider doesn't let me do this.

Apple Mail doesn't let me do this either since none of those contacts have been added to the Contact app.

My email account is IMAP which means most of the emails are still on the server where I could access them with another client. Some have been deleted from the client and the server but are still in the Sent folder of Mail.

The contacts that I'm interested in all have written me through an online form and have a similar subject.

Is there a Mail extension that I could use to achieve this ?

If not, should I combine Mail rules with an AppleScript to do it ?