You should be able to update it by editing the "From address" at Confluence Admin>Mail Servers:
However, it did not work for me, so I opened a bug: From address ignored in Mail Server setup
Please let me know if it works for you as it could be something with my email setup and not with Confluence.
Hi team, I’m Avinoam, a product manager on Confluence Cloud, and today I’m really excited to let the Community know that all customers can now try out the new editing experience and see some of the ...
Connect with like-minded Atlassian users at free events near you!Find a group
Connect with like-minded Atlassian users at free events near you!
Unfortunately there are no AUG chapters near you at the moment.Start an AUG
You're one step closer to meeting fellow Atlassian users at your local meet up. Learn more about AUGs