Are there any best practices recommended by RFC standards for defining mail subjects in PHP?

When defining mail subjects in PHP, it is recommended to follow the RFC standards to ensure compatibility with email clients and servers. One best practice is to keep the subject line concise and relevant to the content of the email. Additionally, it is important to properly encode any special characters in the subject line using functions like mb_encode_mimeheader() to ensure proper display.

$subject = '=?UTF-8?B?' . base64_encode('Your Subject Here') . '?=';