Greylist for FQDN - SmarterTools

Hello there,

So far, I've found SmarterMail only allow IPs and country to be set on Greylist. Is it possible to use FQDN to be set?

Recently our user reported can't get the mail from coremail.cn. And we found from the log the greylisting through different IPs with the same FQDN azure-sdnproxy.icoremail.net. And this behavior led to greylisting failed.

Thanks

rds

Juan Lai

Douglas Foster Replied

5/31/2024 at 5:05 AM

Yes, grey listing would be vastly simplified and more effective if wlit was based on HELO domain rather than IP address, because you would not need to track the IP ranges of large hosting services.

But most mail comes from lmthise large services, so how much value does it add?

Grey listing and exemptions by HELO domain requires verificatio to avoid greylist evasion. That has some complexity, as not all HELO names verify with forward-confirmed DNS. But the complexity is solvable. There are about 5 different ways to do HELO validation, and IP could be used as a fallback when the implemented techniques fail.

Roger Replied

5/31/2024 at 5:40 AM

Yes and ip addresses can change always. FQDN does not so recently

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