Does the email sync between (example) a Mac and Linux?

I have two machines

I think I’m correct in saying that if I install mailspring in both machines then they will NOT sync?

What I mean is: if I create folders then there will be no syncing?

Or - am I wrong?

They should sync if you have created IMAP accounts and is supported by your mail service provider.

As @zigojacko said, the two copies of Mailspring won’t sync with each other directly but, because they’re both syncing with the same email servers, they should be effectively in sync. In other words, they’ll show the same emails and folders, because those are actually created and stored on the remote email server.