Check the timeline first
Confirm the reply appears in the ticket and that the intended recipients and sender mailbox are correct. A draft or failed send cannot reach the customer.
Bounces and automatic replies
If the customer's mail server could not deliver your reply, the reply is marked as bounced on the ticket with the server's own reason, so you know to try another address. An automatic out-of-office reply arrives on the ticket as a private note and does not reopen it or count as the customer writing back.
Verify the domain
Return to Mailboxes and check all required DNS records. SPF or DKIM errors can reduce trust or cause providers to place a message in spam.
Test without customer data
Send a simple message to an address you control, then check inbox and spam folders. Record the time and mailbox if support needs to investigate delivery logs.