Index.razor

@page "/"
@inject IJSRuntime JS
@using System.IO
@using DevExpress.XtraRichEdit
@using MimeKit;
@using MailKit.Net.Smtp
@using Microsoft.Extensions.Logging
@inject ILogger<Index> logger
<div class="container">
    <div class="card mt-3">
        <div class="card-header">
            Word (RTF) Mail Merge
        </div>
        <div class="card-body px-0">
            <DxFormLayout>
                <DxFormLayoutItem ColSpanMd="12">
                    <Template>
                        <p>
                            This example uses the 
                            <a href="https://www.devexpress.com/products/net/office-file-api/word/">Word Processing Document API</a>
                            to generate personalized letters based on a template. Select a sender and click <b>Send emails</b> to send
                            letters to all recipients. Click <b>Download</b> to download a letter in PDF format for a specific recipient.
                        </p>
                    </Template>
                </DxFormLayoutItem>
                <DxFormLayoutItem Caption="From:" ColSpanMd="4">
                    <Template>
                        <DxComboBox Data="@dataSource.SenderList"
                                    TextFieldName="FullName"
                                    @bind-Value="@SelectedSender" CssClass="p-0" />
                    </Template>
                </DxFormLayoutItem>

                <DxFormLayoutItem>
                    <Template>
                        <DxButton Click="SendEmails" Text="Send emails" />
                    </Template>
                </DxFormLayoutItem>
            </DxFormLayout>
            <div class="col">
                <DxDataGrid Data="@dataSource.RecipientList"
                            SelectionMode="DataGridSelectionMode.None"
                            CssClass="mt-3"
                            ShowPager="false">
                    <DxDataGridColumn Field="@nameof(Recipient.ContactName)"
                                      Caption="Recipient" />
                    <DxDataGridColumn Field="@nameof(Recipient.Email)"
                                      Caption="Email" />
                    <DxDataGridColumn Caption="Attachment"
                                      Width="150px">
                        <DisplayTemplate>
                            @{
                                var recipient = context as Recipient;
                                @if (recipient != null) {
                                    <DxButton Text="Download"
                                              CssClass="btn-block" 
                                              Click="@((MouseEventArgs args) => DownloadPdf(recipient))"/>
                                }
                            }
                        </DisplayTemplate>
                    </DxDataGridColumn>
                </DxDataGrid>
            </div>
        </div>
    </div>
</div>

@code {
    RichEditDocumentServer documentServer = new();
    SampleData dataSource = new();
    Sender? selectedSender;

    Sender? SelectedSender {
        get => selectedSender;
        set { selectedSender = value;
            InvokeAsync(StateHasChanged); }
    }

    protected override Task OnInitializedAsync() {
        selectedSender = dataSource.SenderList[0];
        documentServer.LoadDocument("Data/MailMerge.rtf", DocumentFormat.Rtf);
        return base.OnInitializedAsync();
    }
    
    <!--#region CreateAttachment-->
    MemoryStream CreateAttachment(Recipient recipient) {
        ArgumentNullException.ThrowIfNull(SelectedSender);

        using (var resultDocumentServer = new RichEditDocumentServer())
        {
            MemoryStream stream = new MemoryStream();
            // Fill the data table with information about the selected sender
            // and recipient. Use the table as a data source for mail merge.
            documentServer.Options.MailMerge.DataSource = dataSource.GetDataSource(SelectedSender, recipient);
            documentServer.Options.MailMerge.ViewMergedData = true;
            // Execute mail merge.
            documentServer.MailMerge(resultDocumentServer.Document);
            // Export the result to PDF.
            resultDocumentServer.ExportToPdf(stream);
            stream.Seek(0, SeekOrigin.Begin);
            return stream;
        }
    }
    <!--#endregion CreateAttachment-->

    void DownloadPdf(Recipient recipient) {
        // Execute mail merge.
        using (MemoryStream stream = CreateAttachment(recipient))
        {
            // Download letter in PDF format on the client.
            JS.InvokeVoidAsync("exportToPdf", "output.pdf",
                Convert.ToBase64String(stream.ToArray()));
        }
    }
    
    <!--#region SendMessages-->
    void SendEmails(MouseEventArgs mouseEventArgs) {
        // Obtain a list of recipients.
        List<Recipient> recipientList = dataSource.RecipientList;

        for (int i = 0; i < recipientList.Count; i++) {
            // Execute mail merge to generate a letter for each recipient.
            using (MemoryStream attachmentStream = CreateAttachment(recipientList[i])) {
                // Create e-mail message for each recipient.
                // Attach letter to the message as a PDF file.
                MimeMessage message = CreateMessage("YOUR_EMAIL_ADDRESS",
                    recipientList[i], attachmentStream);
                // Send the message.
                SendMessage(message);
            }
        }
    }

    MimeMessage CreateMessage(string from, Recipient recipient, MemoryStream attachmentStream) {
        var message = new MimeMessage();
        // Specify the sender's address.
        message.From.Add(new MailboxAddress(SelectedSender?.FullName, from));
        // Specify the recipient's address.
        message.To.Add(new MailboxAddress(recipient.ContactName, recipient.Email));
        message.Subject = "Your message subject";

        // Create the body of your message.
        var body = new TextPart() {
                Text = "Your message text"
        };

        // Create a PDF attachment to send the generated letter.
        var attachment = new MimePart("application", "pdf") {
                Content = new MimeContent(attachmentStream, ContentEncoding.Default),
                ContentDisposition = new ContentDisposition(ContentDisposition.Attachment),
                ContentTransferEncoding = ContentEncoding.Base64,
                FileName = "attachment.pdf"
        };

        var multipart = new Multipart("mixed");
        multipart.Add(body);
        multipart.Add(attachment);

        message.Body = multipart;

        return message;
    }

    void SendMessage(MimeMessage message) {
        using (var client = new SmtpClient()) {
            // Connect to your SMTP server to send the message.
            // Use one of these ports: 25, 465, 587, or 2525.
            client.Connect("MAIL_SERVER", 587, false);

            // Use the code below if your SMTP server requires authentication.
            client.Authenticate("USERNAME", "PASSWORD");

            try {
                // Send the message.
                client.Send(message);
            }
            catch(Exception ex) {
                logger.LogError(ex.Message);
            }
            finally {
                client.Disconnect(true);
            }
        }
    }
    <!--#endregion SendMessages-->
}