This question was asked over 2 years back but it remains unanswered:
How can I send user who posts via email a confirmation that their message was successfully received and posted?
outofgamut inquires about sending confirmation emails to users who post via email, noting that a similar question from over two years ago remains unanswered. sam responds that while Discourse does not have a built-in mechanism for this specific feature, users in mailing list mode can configure an “echo mode.” This involves selecting the option to “send an email for every new post” within the email preferences, which effectively notifies the user of their activity. Sam advises that for a dedicated confirmation feature, the user should submit a feature request.
This question was asked over 2 years back but it remains unanswered:
How can I send user who posts via email a confirmation that their message was successfully received and posted?
In mailing list mode you can configure an “echo mode”
Particularly by selecting “send an email for every new post” in your email preferences.
However, there is no mechanism built in to Discourse for a “email confirmation” when a message is posted on the forum. I recommend you make a Contribute > Feature request about it.