How to synch my Mail Smart Folders between Macs

It's automagic. Just make sure it is turned on in the iCloud System Preferences.

iCloud does not support or sync Smart Mailboxes or local folders. You can create mailboxes at the iCloud.com site that will be IMAP and show in the Mail sidebar under the iCloud folder. Those will show up on all devices.

Other than that, iCloud will only sync Mail's main mailboxes (default mailboxes).

In Addition to better explain:

Local folders under On My Mac are folders only located on the computer. They are not part of any IMAP or Exchange account.

Smart Mailboxes are for the most part just search engines. Messages are not stored in those, but they merely point to messages which actually reside in the original mailbox where they are stored.

Why did Apple disable such a useful feature as sychronizing Smart Mailboxes and keychains across your macs? This worked fine with MobileMe (about the only thing that did work well). Now with the "improved" iCloud -- we have none of this useful functionality. So only work around seems to be to create identical rules for smartmailboxes on each Mac -- manually?

I think those were done through iTunes before. You can probably still do that with iTunes. I have never done it, so I'm not sure.

I don't understand what you mean. What's "automagic" and where is it found?

In addition, your answer contradicts Leblanc's answer which says it can't be done.

Please clarify.

Nate

The workaround I found was by creating a "rule" on iCloud.com that moves emails that match the created rule to a specified folder. This folder is not a smart folder but will have items automatically moved to it at the server level and therefore the folder and all of its contents will be accessible and have the same content on all devices.