Just to add a clarification about reply-by-email behaviour (since this sometimes comes up in the same context as staged users and moved posts):
Each reply-by-email key is bound both to the post/topic and to the email address of the intended recipient.
If someone forwards or shares their reply-by-email key with another person, the second person will not be able to use it. Discourse checks that the From address on the incoming email matches the address that the key was issued for. If it doesn’t match, the mail-receiver bounces the message back with an error like:
We’re sorry, but your email message to
reply+8ea3c4377a64fd24270449c9815ae5e7@discourse.example.com
didn’t work.
Your reply was sent from a different email address than the one we expected, so we’re not sure if this is the same person. Try sending from another email address, or contact a staff member.
This ensures reply keys cannot be passed around as a way to impersonate another user.
By contrast, when you’re dealing with staged users created from incoming mail (as in the OP), those are handled differently: if auto-create staged users is enabled and the message is sent to a category address (not via a reply key), then Discourse will happily stage a new account for that sender. But reply-by-email keys always require the sender’s address to match the originally issued key.
From: Ethan’s Community reply-to-me-by-email@discourse.REDACTED.com
Sent: Thursday, September 11, 2025 7:34 pm
To: ethan.tees@btinternet.com ethan.tees@btinternet.com
Subject: [Ethan’s Community] Email issue – Unexpected Reply Address
We’re sorry, but your email message to [“reply+ancdc4377a64fd37s25449c9815ae5e7@discourse.REDACTED.com”] (titled test any subjective) didn’t work.
Your reply was sent from a different email address than the one we expected, so we’re not sure if this is the same person. Try sending from another email address, or contact a staff member.
Error in admin logs: email::Receiver::ReplyUserNotMatchingError