How to delete messages in Gmail (not move to Trash folder) using MailKit

Question

I'm trying to develop an ImapClient using the MailKit library.

How can I permanently remove messages from a Gmail account as opposed to simply moving them to the Trash folder?

Answer 1

On most IMAP servers, the way you would do this is:

folder.AddFlags (uids, MessageFlags.Deleted, true);

This sets the \Deleted flag on the message(s). The next step would be:

folder.Expunge (uids);

This would purge the message(s) from the folder.

Assuming that this does not work on GMail, it's probably because as soon as you add the \Deleted flag to a message on a GMail IMAP server, it moves it to the Trash folder (which is beyond the IMAP client's control).

Here's an idea that might work, however...

// First, get the globally unique message id(s) for the message(s).
var summaries = folder.Fetch (uids, MessageSummaryItems.GMailMessageId);

// Next, mark them for deletion...
folder.AddFlags (uids, MessageFlags.Deleted, true);

// At this point, the messages have been moved to the Trash folder.
// So open the Trash folder...
folder = client.GetFolder (SpecialFolder.Trash);
folder.Open (FolderAccess.ReadWrite);

// Build a search query for the messages that we just deleted...
SearchQuery query = null;
foreach (var message in summaries) {
    var id = SearchQuery.GMailMessageId (message.GMailMessageId);
    query = query != null ? query.Or (id) : id;
}

// Search the Trash folder for these messages...
var matches = folder.Search (query);

// Not sure if you need to mark them for deletion again...
folder.AddFlags (matches, MessageFlags.Deleted, true);

// Now purge them from the Trash folder...
folder.Expunge (matches);

And you're done...