O365 email local cache

Work uses O365 and I'm getting a little frustrated with OWA. Thinking about running a local email server to mirror O365. In the end, I want to keep my email in O365, but have a 2 way sync with a local imap server. Looks like I have a few options on the email server - dovecot/cyrus/stalwart. For the syncing, I just see...