The following file types are supported for native file attachment: Adobe Portable Document Format (PDF), Microsoft Office Word (DOC, DOCX), PowerPoint (PPT, PPTX) and Excel (XLS, XLSX), Plain text (TXT), Tagged Image Format (TIF), Hypertext Markup Language (HTML), Rich Text Format (RTF), Postscript (PS), JPEG (JPG), Graphics Interchange Format (GIF), Bitmap (BMP)