public ImapSequenceSet GetSequenceOrUidSet(ImapOpenedMailboxInfo mailbox)
            {
                ImapMatchedSequenceSet matchedSequenceNumbers;

                mailbox.ProcessResult(mailbox.Client.Session.Sort(sortOrder,
                                                          searchCriteria,
                                                          encoding,
                                                          out matchedSequenceNumbers));

                return matchedSequenceNumbers;
            }
            public ImapSequenceSet GetSequenceOrUidSet(ImapOpenedMailboxInfo mailbox)
            {
                ImapMatchedSequenceSet matchedSequenceNumbers;

                if (mailbox.Client.IsCapable(ImapCapability.Searchres))
                  mailbox.ProcessResult(mailbox.Client.Session.ESearch(searchCriteria,
                                                               encoding,
                                                               ImapSearchResultOptions.Save,
                                                               out matchedSequenceNumbers));
                else
                  mailbox.ProcessResult(mailbox.Client.Session.Search(searchCriteria,
                                                              encoding,
                                                              out matchedSequenceNumbers));

                return matchedSequenceNumbers;
            }