Adding unsubscribe or subscribe link from MailPoet Newsletters WordPress plugin in custom mail(Php mail)?

I have searched everywhere but not found any solutions. I also tried below code but its not working. Can anyone help on this?

 <?php if(get_user_meta($current_user->id,'wdm_subscribe',true) == 'no'): ?>
 <p>
    <a href="/my-account/?wdmsubs=true" value="subscribe" name="subscribe" id="wdm_subscribe">Subscribe</a>
 </p>
 <?php else: ?>
 <p>
    <a href="/my-account/?wdmsubs=false" value="subscribe" name="subscribe" id="wdm_subscribe">Unsubscribe</a>
 </p>
 <?php endif; ?>