Best way to create an archive/backup of my Apple Mail to the cloud

In the light of the recent fires in L.A., I've been looking at ways to create off-site snapshots of important files. My email archive is definitely important. I have multiple email addresses on my Mac so that complicates things immediately. I've also organized the forty years of old email (yes, that's old stuff but I've saved myself a lot of grief being able to pull things up from way-back) into folders. Often folders within folders. So, while organized, it's complicated. I already have a time machine backup of everything but that drive is local. I have cloud storage available to me which I can use immediately. So rather than try to replace time machine with a cloud solution, I'd rather once in a while get a snapshot of the entire Mail archive and push it to the cloud in case the entire neighborhood goes up in flames. In my early experiments, I've found that just selecting my folders and selecting Export does virtually nothing. No attachments or folders and their contents seem to be saved. So am I dreaming? There must be a way to get ALL my email out and into some kind of recoverable format in case of a disaster.