DNS/PTR Mismatch and SPF record
Posted on 2012-03-21
I am having issues emailing some customers. The error I receive is the following:
You do not have permission to send to this recipient. For assistance, contact your system administrator.
<hercules.domain.local #5.7.1 smtp;554 5.7.1 Sender DNS/PTR Mismatch: IP Address for PTR Hostname does not match sending IP:[75.x.x.x] - Possible Forgery>
I did not configure our DNS records originally and I believe certain records such as SPF and PTR are not configured correctly.
Our mx record points to MXlogic. So any incoming email goes to MXlogic/McAfee to be scanned. Our exchange server is mail.mydomain.com and points to 75.x.x.30. Our Exchange server is behind our firewall which has an ip of 75.x.x.20 so this is the IP other SMTP servers will see our emails coming from.
This is where I am confused. If I do an nslookup for 75.x.x.20 I get host162.mydomain.com and I don't even know where the name came from. If I do an nslookup for host162.mydomain.com I get the ip of my www record which does not match my firewall ip 75.x.x.20. I don't have the host162.mydomain.com on Network solutions so I am assuming this is a record at the ISP. I am wondering if the mismatch is because the IP where my emails are coming from resolves to a record which its IP does not match the sender IP in this case 75.x.x.20.
What is my outgoing IP (75.x.x.20) supposed to resolve to? mail.mydomain.com?
mail.mydomain.com is currently pointing to 75.x.x.30 and the record is used by MXlogic to forward our incoming emails.
The other thing that happens is if I do a test connectivity using textexchangeconnectivity.com and use the outbound emial test, the result comes back with everything ok except for the SPF record that it is not found. The test asks me for the outgoing ip so I use 75.x.x.20.
If I do a SPF test using mxtoolbox and use mydomain.com it doesn't find anything, but if I use mail.mydomain.com it finds the following:
Type Domain Name TTL Record
TXT mail.mydomain.com 2 hrs v=spf1 mx ip4:75.x.x.20 ~all
TXT mail.mydomain.com 60 min v=spf1 ptr include:mxlogic.net ~all
Record: v=spf1 mx ip4:75.x.x.20 ~all
Prefix Type Value Prefix Desc Description
+ mx Pass Match if IP is one of the MX hosts for given domain name
+ ip4 75.x.x.20 Pass Match if IP is in the given range
~ all SoftFail Always matches. It goes at the end of your record.
reverse lookup smtp diag blacklist port scan