html emails aren't shown correctly

Hi vahid, 

Can you go to <dw-question-answer-folder>/inc/notification.php, line 133 and please make sure this line have the content like this:

$headers .= "From: " . $from_email . "\r\n";

instead of ( without dot “.” character before “=” )  :

$headers = "From: " . $from_email . "\r\n";

If you still meet this problem, please update your file by this https://github.com/designwall/dw-question-answer/blob/master/inc/notification.php. 

Regards