Response Content type as CSV

Using text/csv is the most appropriate type.

You should also consider adding a Content-Disposition header to the response. Often a text/csv will be loaded by a Internet Explorer directly into a hosted instance of Excel. This may or may not be a desirable result.

Response.AddHeader("Content-Disposition", "attachment;filename=myfilename.csv");

The above will cause a file "Save as" dialog to appear which may be what you intend.

MIME type of the CSV is text/csv according to RFC 4180.

Use text/csv as the content type.

Over the years I've been honing a perfect set of headers for this that work brilliantly in all browsers that I know of

// these headers avoid IE problems when using https:
// see http://support.microsoft.com/kb/812935
header("Cache-Control: must-revalidate");
header("Pragma: must-revalidate");

header("Content-type: application/vnd.ms-excel");
header("Content-disposition: attachment; filename=$filename.csv");

Try one of these other mime-types (from here: http://filext.com/file-extension/CSV )

• text/comma-separated-values
• text/csv
• application/csv
• application/excel
• application/vnd.ms-excel
• application/vnd.msexcel

Also, the mime-type might be case sensitive...