defer-om-embed-wordpress.php

function your_prefix_om_defer_script( $campaign_embed ) {

	$campaign_embed = str_replace( 's.async=true;', 's.defer=true;', $campaign_embed );

	return $campaign_embed;

};

add_filter( 'optin_monster_campaign_embed_output', 'your_prefix_om_defer_script' );

add_filter( 'optin_monster_embed_script_tag', 'your_prefix_om_defer_script' );