PHP e-mail does not change line

Content-type: Defines how the user's browser or related device Displays the data that will be loaded, or how to handle the data that will be loaded

The Mime:mime type is the type of file that sets an extension that is opened by an application, and the browser automatically opens with the specified application when the extension file is accessed. Many are used to specify some client-customized file names, as well as some ways to open media files.

Text/html means that the content-type of the file is set to the form of text/html, and the browser automatically calls the HTML parser to process the file when it obtains the file.

Text/plain means that the file is formatted as plain text, and the browser does not process the file when it obtains it.

$headers. = ' Content-type: '. $content _type. '; Charset=shift-jis '. "\ r \ n";

PHP e-mail does not change line