Good question - you are a very responsible person for checking this! No one can ever use/create the email address again within the VM system.
The mailbox and data SHOULD be deleted, although this does not always happen. If you are concerned, run the address through https://mailtester.com. If Red, then the mailbox is deleted. If green, come back and ask the Forum Team (VM employees) to perform a manual deletion.
Hello, This is a follow on to the advice I got about deleting a secondary email account yesterday. I have been on mailtester and it is still 'green' today. How long does it take to be 'red' after taking the delete action from the main account? Thanks.