Searching IMAP and EWS for emails that are NOT UID

+1 vote
asked Mar 5, 2016 by SeToY (520 points)


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.


Applies to: Rebex Secure Mail

1 Answer

0 votes
answered Mar 8, 2016 by Tomas Knopp (58,890 points)
selected Mar 8, 2016 by SeToY
Best answer


unfortunatelly neither EWS, or IMAP protocol have support for directly searching for messages according to their UniqueID/EWS ID.

So you have to search for all the messages that arrived at the specific date (or according to other criteria). This will give you a list from which you have to filter out yourself the messages that already have been processed.

Something like this:

Dictionary<string, bool> processedUIDs = new Dictionary<string, bool>();

// search for messages that arrived today
ImapMessageCollection list = imap.Search(ImapSearchParameter.Arrived(DateTime.Now));
ImapMessageCollection filtered = new ImapMessageCollection();

foreach (var messageInfo in list)
    if (!processedUIDs.ContainsKey(messageInfo.UniqueId))

    // now work with the filtered collection