Prevent deletion of messages during sync per-folder?

[Will Styler]

Hello all,

My apologies for a rather user-directed question, but I'm so far unable to find a way that I can ask offlineIMAP to decline to delete local copies of a message from certain folders, for instance, "Trash".  My IMAP provider (MobileMe) has recently started clearing messages older than 30 days from the server, and I'd like the local trash folder to keep a long-term archive for referencing elsewhere.  

I've phrased this as being folder-specific as we clearly don't want to enable this everywhere, or a message removed from the INBOX would never be removed, and messages from already-archived second folders would persist even when removed, but for those of us wanting a trash archive (which could still presumably be culled using Mutt acting on the local folders), this seems like the best idea.

However, I'm aware that this could be difficult to implement, as OfflineIMAP would then want to sync all those messages which it has kept and the server hasn't back up to the server during the next sync (unless they were marked somehow as "local-only".  So, as a secondary (and perhaps easier) option, is there a way to create a local folder which mirrors the trash folder (but has no deletion) and is not synced back to the server?

Thanks, and I apologize if this is a silly question or isn't the forum for it,

Will