[질문]메일 스팸 필터와 관련

저희 회사에서 메일서버를 구축해준 회사의 메일 문제인데요~

외국 회사에 메일을 보내면 메일발송이 되지 않아 그쪽에 문의한 결과가 메일로 왔는데... 해결 방법을 잘 모르겠습니다~ 메일 내용을 올리니 고수분들 보시고 답변 부탁드립니다~ 참고로 전 리눅스 메일서버 처음 봤어요 -_-;;;

"메일 원문"

"Mike, I am researching why the two Fuji domains cannot send us email.
I'm still waiting for info on the fujitrading.nl domain, but I have an answer for the fujitrans.co.kr domain.
Chevron has implemented a new spam filtering system (Ironport) which will not accept any email from a domain that does not have a reverse DNS (PTR) entry.
Please send this email to your contact at fujitrans.co.kr and ask him to forward it to his email support team.
We will not be able to accept email from them until the PTR entry has been added.
Following is information from www.dnsstuff.com for that domain.
FAIL Reverse DNS entries for MX records ERROR:
The IP of one or more of your mail server(s) have no reverse DNS (PTR) entries/* (if you see "Timeout" below, it may mean that your DNS servers did not respond fast enough)*/.
RFC1912 2.1 says you should have a reverse DNS for all your mail servers.
It is strongly urged that you have them, as many mailservers will not accept mail from mailservers with no reverse DNS entry.
You can double-check using the 'Reverse DNS Lookup' tool at the DNSstuff site if you recently changed your reverse DNS entry (it contacts your servers in real time;
the reverse DNS lookups in the DNS report use our local caching DNS server).
The problem MX records are:
35.47.84.220.in-addr.arpa [No reverse DNS entry (rcode:
3 ancount:"

감사합니다 ^.^