id,summary,reporter,owner,description,type,status,priority,milestone,component,version,severity,resolution,keywords,cc,focuses 39775,wp_mail miss send Content-Type with boundary when array header does not have other custom headers,kn007,,"It's a PR send in github. https://github.com/WordPress/WordPress/pull/273 Fix empty charset in line 436. Before: `Content-Type: multipart/alternative; charset=` After: `Content-Type: multipart/alternative; charset=UTF-8` ------------- fix `$headers[] = ""Content-Type: multipart/alternative; boundary=\""$boundary\"""";` not send when not other headers. Test Code: {{{#!php ""; $headers[] = ""Content-Type: multipart/alternative; boundary=\""$boundary\""""; $body = ""--$boundary\r\n"" . ""Content-Type: text/plain; charset=UTF-8\r\n""; $body .= 'test'; $body .= ""--$boundary\r\n"" . ""Content-Type: text/html; charset=UTF-8\r\n""; $body .= '