FCrDNS shouldn't allow CName

Seeing a decent amount of spam from IP addresses that fail FCrDNS. However, when I look at the SmarterMail spam score on these messages, there are no points added for FCrDNS.

If you plug the IPs into MultiRBL, it shows "No Record Found - Failed" for FCrDNS. Here are some example IPs:

142.202.188.114
142.202.188.117
209.126.105.20

I'm not a DNS guru, but looks like these IPs are using CName records to trick SmarterMail. According to RFC, PTR records must point back to a valid A record, not an alias defined by a CNAME.

So request that SmarterMail adjust the check to only allow A or AAAA records for FCrDNS. Thanks!

Brian Bjerring-Jensen Replied

Today at 1:20 PM

Getting increased amount of spam on 9124 versus 8930.

Kyle Kerst Replied

Today at 3:44 PM

Employee Post

Do you have some example EMLs we could take a look at? I know they won't help us simulate rDNS/forward confirm but they may allow us to find examples of it happening in our own environments that we can use to find a solution for you.

Kyle Kerst IT Coordinator SmarterTools Inc. www.smartertools.com

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