Backing up Helm email locally

I’m currently a POP3-guy with my e-mail stored locally in an Outlook .pst file and backed up regularly, but I will cautiously venture out into the 20th century by converting to IMAP when I get my Helm 2.0.

I know Helm provides encrypted cloud backup, but being a belt-and-suspenders kind’a guy, I like to have at least two backups. If I lose my data, I am literally out of business. Outlook 365 saves IMAP mail locally in an .ost file for offline reading and I will certainly backup that. Does anyone know if mail can be recovered from an .ost file in the event data on both the Helm and the Helm’s cloud backup gets corrupted?

If you aren’t married to using outlook to do your backups, you could use a tool like imapsync to make copies of all your mail hierarchy. I use this when i move from 1 mail server to another.
As a bonus, it can store things as plain text files so you aren’t locked to a specific tool in the future.

Local backups sound nice, but higher priority for me would be a way to verify the cloud backups are restorable. Right now it’s very much a blind faith exercise. I think the only way to test it would be to get a second Helm box and try it. With more faith in the cloud backups I’d feel less serious about a local backup option.

As it is a local backup would bring some confidence for me.