Spamrats

I agree with yggdrasil, but would start with the organisation you need to contact and ask the recipient to add your domain name to their Approved Sender's list. If their mail service doesn't support approved senders you probably need to contact your email provider and ask them to investigate. I wouldn't get involved with SpamRATS. If you use gmail (it's useful to read even if you don't use gmail), here is an informative link:- support.google.com/a/answer/27642?hl=en

I'd be more inclined to contact your ISP, with full headings etc. Or phone the organisation you need to contact