bp_email_custom_metaboxes()

function bp_email_custom_metaboxes() {
	// Remove default 'Excerpt' metabox and replace with our own.
	remove_meta_box( 'postexcerpt', null, 'normal' );
	add_meta_box( 'postexcerpt', __( 'Plain text email content', 'buddyboss' ), 'bp_email_plaintext_metabox', null, 'normal', 'high' );
}