What happens to my FTP accounts created before I switch to the permanent domain?

PRESSERO > *Pressero FAQs
Individual ftp account names created using Pressero admin, are created with the hostname that existed at the time they were created; if the hostname changes, they must be destroyed and recreated to pick up the new hostname.

You can connect to "ftp.domain.com" and log in as "somebody@domain.v4.pressero.com" ... but if you want to log in as "somebody@domain.com" you need to recreate the name through Pressero admin.