Is there a way to automate Gmail?

Hi guys, I need a way to "automate" my Gmail accounts. I receive 100 - 250 mails per account and I need to reply to everyone of those mails with the same text message.

The messages I receive are coming from a website (Through which people are contacting me).

Using the "away reply" doesn't work because I only need to reply to the very first message they send me. (After my first message I should not reply even if they send me another email)

Neither can I use the gmail bulk reply extension on Chrome because it doesn't work since I can not put all the messages in one CC as all the email addresses I see are censored. They look something like this: fran*****@website.com.

Currently I reply manually but it just takes too much of my time.

Maybe some of you can help me here.
Maybe a script would do this?

Thank you guys.

Seems like I have sold this Issue! Admins you can close this thread please!

P.S.

I am using the chrome extension batch reply.

Try this https://developers.google.com/gmail/api/ , i never noticed that there's actually an API for gmail. No mentions of usage rate limit tho