According to Grace Note, automated mails which state that Stack Exchange has received your mail are redundant and are not sent (said on 23rd May, 2017).
When you reach out through Contact Us, you receive the following confirmation message. Sending a followup email that just echoes that seems redundant and not particularly any more convincing.
But, I recently got a mail like this after contacting SE staff using the contact page in Ask Ubuntu:
We are confirming that your request has been received. You do not need to reply to this message unless you have further information to add.
So, since when did Stack Exchange start sending automated emails like the above one?