Internal notes are never shown in the customer portal. Customers also don't see the ticket's priority, category, assignee, tags, or custom ticket fields.
When a customer opens a ticket, they see its number, subject, status, and creation date. Below that is the conversation: the original message and every reply. Attachments on these messages are shown too.
Emails your team adds with the "Forward email to this ticket" option also appear in the conversation, with their sender, subject, and full content. Emails sent by your automation rules are not shown.
Replies from your team show the team member's name and profile picture, even if your mailbox sends emails under your company name or another sender name.