I just configured Wordpress using Mailpoet's premium package. It had an easy way to configure DKIM (an email authentication method). XF forums send a lot of email. It would be good to have such easy setup here, too.
While this is true, you can also add DKIM signatures at the PHP level if you don't have access / ability to configure your MTA. Yes, you should always add your DKIM signature at the MTA level if at all possible, but if it isn't possible, adding it to your PHP software is a good alternative and works just as well. @rebelde this is a good idea.