当我使用php邮件功能发送电子邮件时，html电子邮件在电子邮件（gmail除外）中没有以正确格式显示

I am new in php and trying to send email via php mail function. In gmail account email is displaying properly but other than gmail I received html tags as text in email body.

Here is my code snippet:

$headers  = 'MIME-Version: 1.0' . "
";

$headers .= 'Content-type: text/html; charset=ISO-8859-1' . "
";

$headers .= "Reply-To:abc@abc.com" . "
";

$headers .= "BCC: $bcc" . "
";

$headers .= "From: $from" . "
";

mail function which I am using is:

mail( $to, $subject, $body, $headers )

Got the solution, I just replaced ' ' with ' ' and it started working perfectly for every mailbox.

Thanks