I’m still waiting for a reply from Interia, WP.pl, and Inbox.lv/lt on whether you need to use webmail every X days with the free account or if purely connecting from a mail client counts as being “active”. Libero.it doesn’t have a way to contact them without creating an account first.
My suspicion is that IMAP should be fine to keep the account alive, but confirmation would be better. (I think this is very important for “not my main email but also not a throwaway” accounts. My Tuta account got deleted because I forgot to log in to the webmail regularly!)