I almost can't believe this isn't a feature as it works on all other ticket systems we've used.

In Zoho Desk, if we raise a ticket for a customer and attach a file, an email is sent to the user, but no attachment is sent. This is really quite simple and surely it must be popular.

The only option given to us by Zoho is to 1) Create the ticket then 2) reply to the ticket with the attachment.

Example use case: Sending a design for approval to a customer.