Automated reply to attached email

Are you creating a record in Airtable for every email you receive or something?  Could you provide some screenshots of your tables and some example data?

Yes, I saved every price request email in *.msg format and uploaded it to record. After the estimate upload the offer letter to the same record. Then I changed the record status to submitted. When I change the status to submitted I need to reply to that original email with thanking for the request, and also attach the offer letter. 

Hmm, does the record contain the person's email address?  If so, you could trigger an automation when the record status changes to "Submitted" and send out an email using the Send Email action: https://support.airtable.com/docs/send-an-email-action

If the person's email address only exists within the .msg file then I think you'll need to use scripting or some third party tool to help you extract the email address from the file and update the record with it

I'm using that same method and there is a manually entered column for clients email.  Now, when I change the status to "Submitted" automated email is sent to the clients. That is a fresh email and not a reply email for the client's email. That's what I need to avoid. 

Ah I see!  To do that I think you're going to need to have the email's ID stored with the record, and then your automation would need to hit an external service like Zapier or Make.  That external service would then use the email ID to find the appropriate email in your email provider, and then reply to it from there.  Should work!