The issue involves email notifications sent to a contact email (routed to a group) being rejected with an Email::Receiver::AutoGeneratedEmailError. hellekin reports this as a bug, expecting the group to receive notifications without rejection. maiki clarifies that the contact email isn’t set to a group but routed to one, and suggests checking block auto generated emails and auto generated allowlist settings. hellekin acknowledges the autogenerated_allowlist setting and suggests it should include internal senders by default. maiki explains that defaults are intentionally empty, allowing site operators to customize handling; they personally block auto-generated messages and question the usefulness of “update available” notifications for non-admins. hellekin agrees such messages are irrelevant for non-admins and finds the error message confusing — allowing the sender would flood the group inbox, echoing concerns from an existing topic. They plan to draft a feature request to improve the experience.
When contact email is set to a group
And the group receives a notification (e.g., Update available)
Then the email notification is rejected with Email::Receiver::AutoGeneratedEmailError
The group should be notified (either by internal notification or email notification).
No email should be rejected.
To clarify, the contact email setting is not “set to a group”, it sends an email, which is routed to a group.
Two settings you might check:
block auto generated emailsauto generated allowlistYou should be able to add the email from your site so auto-generated messages are sent through. 
I didn’t know about the autogenerated_allowlist setting, thank you! I thought it was a bug because it’s an internal email sender, so I guess it should be in that list by default.
With the current, empty defaults, we leave it to site operators to adjust auto-generated message handling in Discourse.
I for one do not accept auto-generated messages in my Discourse sites. 
This sounds like an interesting use-case, but not one that I know of; perhaps we just need better messaging/notifications around certain actions… although I presumed admin users are notified about updates (I know I am!), and non-admin users would not be able to do anything with an “update available” message…? 
I’m sure a Contribute > Feature topic explaining the situation would be appreciated.
I agree this type of messages is not useful for non-admins. But it’s also weird to see an error message for that. I could allow the source to get rid of the error, but then an irrelevant message would reach the contact group inbox. There’s already a topic complaining about Contact email receives too much notifications.
I will think about a feature formulation.