The API allows you To add watermark To all the attachments of supported types in an Email message as shown in the following code sample.
advanced_usage.add_watermarks_To_Email_attachments.EmailAddWatermarkToAllAttachments
TextWatermark watermark = new TextWatermark("Test watermark", new Font("Arial", 19)); EmailLoadOptions loadOptions = new EmailLoadOptions(); // Specify an absolute or relative path To your document. Ex: "C:\\Docs\\message.msg" Watermarker watermarker = new Watermarker("message.msg", loadOptions); EmailContent content = watermarker.getContent(EmailContent.class); for (EmailAttachment attachment : content.getAttachments()) { // Check if the attached file is supported by GroupDocs....Conversion Product Solution GroupDocs...watermarks to email attachments Add watermarks to email attachments...