Searching IMAP and EWS for emails that are NOT UID

Hello,

I'm currently searching IMAP and EWS objects to return emails arrived at a specific date.

However I now want to search for e-mails that arrived at a specific date and are not already synchronized. For that I have a list of UniqueIds that have already been sychronized.

How can I search IMAP and EWS for that? I tried using ImapSearchParameters.Not and EwsSearchParameters.Not, but to no avail. It doesn't offer an "Id" or "UniqueId" parameter.

Thanks!