message seen files (old mailbox to new mailbox name)

[Adam D]

I have renamed a mail box from user/username to user/username at domain.tld
and noticed the seen mail setting were lost or not using the old
username.seen file.  In an email client I select a mailbox all the once
seen mail are now shown as unread.  I selected all mail and marked it as
seen but when I look into the /var/lib/cyrus/user/(A-Z,a-z), the newly
marked mail are not saved to a file I can find.  Can I convert the seen
mail over to the new mail box so they are in sync to the old seen file
and where would the new created seen file be located?

-Adam