so... first.. what SM version are you on. 

and second,  for your server to send out  emails .. yes you  will have to reverse DNS set AND, usually your broadband provider, has to put in reverse look-up for your server on their end as well.

I have this exact same question!

I believe they are saying your upstream provider (whoever owns your IP block) needs to setup the PTR records on their end. Unless they delegate PTR control to you, then you can set it up. If not, you need to setup the correct forward DNS records and then your provider set the PTR records on their end.

OK, for those that might stumble on this thread in the future.   Here is how I solved this issue, and attained a perfect SpamAssassin score with our multidomain mail system.

1) Yes, PTR must be set up by hosting provider,  and the IP you should be using is the publicly exposed mailserver IP (can be obtained by taking your RAW email header and put it into any email header analysis website). This will show the IP and main host header you are expressing in your SMTP banner via SmarterMail.  There is only one expressed, even if you have 50 domains.

2)  The second important, and key point, is that you must setup DNS record for that host header record (mine is securemail.stevemail.com)   and the IP address used in the dns record of securemail.stevemail.com  MUST be the same as what is being expressed in your SMTP banner.

Those to reverse DNS and forward DNS settings must match, and then you are golden.  I saw someone illustrate the records like this: 

   host header domain >>>> 344.24.12.761    must match

 344.24.12.761   >>>> host header domain

A good email testing system is http://www.mail-tester.com