PTR record is used to map an IP address to a fully qualified domain name (FQDN). So basically the opposite of what an IP address does.
If you are worried about email spoofing, you may also want to set up an
SPF2 record, which if set to a hard fail will also prevent spam being spoofed from your IP address/domain name.
However with regards to sending out bulk emails, from experience I would say don't. Firstly your IP address could easily be reported and blacklists which could interfere with your normally day-to-day emails being sent straight into the spam box.
You would be better off paying a little every month for an email manager which has already put all the effort in to getting their IP address white-listed. The last thing you want is to get your order received emails spammed as you have sent out a marketing campaign and a few too many people reporting it. My final point being that your ISP may also complain, as ours did, about the amount of emails sent out in such a short space of time - they also blocked our IP from sending emails temporarily.
So answering your question: A
PTR record should resolve your IP to your FQDN. You can check your
PTR record here to verify it.
With regards to setting up
SPF records, please see here for more information. But if you want to use an
SPF wizard to create the record for you, you can use one like here.