You refer to it as a "backup account", but it doesn't sound like a backup if it was the only place those messages were stored. I use gmail as my primary email

You refer to it as a "backup account", but it doesn't sound like a backup if it was the only place those messages were stored. I use gmail as my primary email client, and use both a gmail.com address and several of my own domains. But I regularly sync everything to a local email client (Thunderbird), so that even if Google cut me off, I would have access to all but my most recent emails, and to all my contacts.