Hi,
if your emails are being returned undeliverable, then the issue is most likely not what you think it is, but something else entirely. I can take a look at your server, see what the issue is and resolve it, if it can be resolved on the server end (sometimes it can't). Will just need the bounced emails to check.
SPF, DKIM, domainkeys and RDNS won't ever "bounce" your mail. They will move to junk, but never bounce your mail.
If you'll look at my profile (https://www.freelancer.com/u/twhiting9275.html), you'll see 100% positive (5 star) feedback, high completion (I don't abandon projects, but there are times employers take work and cancel to avoid paying) and a link to my own site where I've done the same for better than 10 years now. Your project will be completed with the same diligence and persistence. Your task will be completed within the advertised period of time, and be given everything needed to be done right.
I look forward to hearing from you and working with you on this project.
Tom Whiting