If the enable staged users and the email in Site Settings are enabled on your forum, staged users are created automatically when they send an email to create a topic on your forum. For details about the email in Site Setting, see: Start a New Topic via Email ✉.
On the meta forum, the Discourse team has enabled incoming emails to be posted a group. When emails are sent to our group’s incoming email address, staged users are created.
The benefit of this is that it allows the whole Discourse team to participate in answering support requests directly from Discourse. This lets us use Discourse tools to manage support requests - we can assign tasks to members of the team, tag messages to allow us to sort them later, search messages with the in:private search filter, communicate privately within messages if we have questions that need to be answered by another team member… It’s a huge improvement over trying to handle communication through an email client.