How to auto-reply to reply-to field?

Question

I would like send auto-reply mails to email addresses written in reply-to field. How this can be achieved?

  Sample Mail Received :
 
 from:  abc@gmail.com
 reply-to:  def@gmail.com
 to:    ghi@gmail.com
 date:  Aug 31, 2020, 12:43 AM    

By using the template and filter options I am able to send auto-reply e-mails to addresses written in from field (abc@gmail.com in this case). But I am not able to figure how to send auto-reply to addresses written in reply-to field (def@gmail.com in this case).

Answer 1

Google does not support this.

It is possible write a Google Apps Script, possibly/probably including the Gmail API , to generate an email that has the appearance of being an auto-reply (a "pseudo-autoreply"). There are many precedents for this. However these do not have the character of auto-reply emails, and they have some inherent limitations.

• auto-reply is triggered when an email is received. Apps Script has no equivalent; however depending on the "urgency" of generating the pseudo-autoreply, a time-driven trigger might be used to scan the inbox and execute the script.
• auto-reply does not mark the relevant message as "read". Depending on your needs, a pseudo-autoreply might need to avoid marking a message as read but in that case, it would need to label that message in such a way so that auto-replies are not continuously sent for that message. One option might be to use a single purpose-use label to denote that an autoreply has been sent.
• an auto-reply does not become part of any message thread. A pseudo-autoreply would need an appropriate title to avoid being added to a thread.
• genuine auto-replies have certain mail header values that identify their function, such as (but not limited to):
  • X-Autoreply
  • Auto-submitted