Microsoft.Exchange.WebServices.Data.EmailMessage error "The operation can't be performed because the item is out of date. Reload the item and try again"

I have a work around.

I noticed that when the error occured, the mail was in the drafts folder, but got stuck there.

Work around;

Step 1 : instead of message.send() or message.sendandsave() , use message.Save(WellKnownFolderName.Drafts);

Step 2 : read the drafts folder (you can make a filter list of the mails in the drafts folder) and sendandsave() the drafts mail.

        try

        {

            var cca = ConfidentialClientApplicationBuilder

                                        .Create(L_FactuurmailAppid)

                                        .WithClientSecret(L_FactuurmailClientSecret)

                                        .WithTenantId(L_FactuurmailTenant)

                                        .Build();

            var ewsScopes = new string[] { "https://outlook.office365.com/.default" };

            var authResult = cca.AcquireTokenForClient(ewsScopes).ExecuteAsync().GetAwaiter().GetResult();

            ExchangeService exchange = new ExchangeService(ExchangeVersion.Exchange2013_SP1);

            exchange.Timeout = 100000000;

            exchange.Url = new Uri("https://outlook.office365.com/EWS/Exchange.asmx");

            exchange.Credentials = new OAuthCredentials(authResult.AccessToken);

            // exchange.ImpersonatedUserId = new ImpersonatedUserId(ConnectingIdType.SmtpAddress, L_FactuurmailFrom);

            exchange.ImpersonatedUserId = new ImpersonatedUserId(ConnectingIdType.SmtpAddress, "your_email_adres@test.com");

            exchange.Timeout = 1000000;

            exchange.KeepAlive = true;

            //// verstuur alle mails uit DRAFTS FOLDER

            // Bind to the Drafts folder

            FolderId draftsFolderId = new FolderId(WellKnownFolderName.Drafts);

            // Define a search filter for the subject containing "your_mailsubject_selection_text"

            SearchFilter searchFilter = new SearchFilter.ContainsSubstring(ItemSchema.Subject, "your_mailsubject_selection_text");

            // Define the item view to specify the number of items to retrieve

            ItemView view = new ItemView(100); // Adjust the number if needed

            // Find items in the Drafts folder matching the search filter

            FindItemsResults<Item> draftItems = exchange.FindItems(draftsFolderId, searchFilter, view);

            foreach (Item item in draftItems.Items)

            {

                if (item is EmailMessage draftEmail)

                {

                    // Send the email

                    draftEmail.SendAndSaveCopy();

                }

            }

        }

        catch (Exception ex)

        {

            MessageBox.Show("Sending from DRAFTS FOLDER failes !\n" + ex.Message.ToString());

        }
```Hope this helps

Additional notice:

I was too optimistic. I had to build a loop around the emails in Drafts folder untill Drafts folder is empty