Setting mime type for excel document

Question

MS Excel has the following observed MIME types:

• application/vnd.ms-excel (official)
• application/msexcel
• appli

Answer 1

I am using EPPlus to generate .xlsx (OpenXML format based) excel file. For sending this excel file as attachment in email I use the following MIME type and it works fine with EPPlus generated file and opens properly in ms-outlook mail client preview.

string mimeType = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet";
System.Net.Mime.ContentType contentType = null;
if (mimeType?.Length > 0)
{
    contentType = new System.Net.Mime.ContentType(mimeType);
}