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How to whitelist IP addresses for email routing.

LuisGonzalezLTLuisGonzalezLT Posts: 6 Spectator
edited October 2022 in Email Sep 13, 2022

For two weeks now email I send out from my HostGator hosted email account gets rejected due to Cloudmark CSI-Global blacklisting. HostGator tech support said I needed to talk to my ISP tech support and have them whitelist the IP addresses with Cloudmark. The addresses I have had issues with so far are:

Some example error messages below showing the blacklisting:

host Delay reason: SMTP error from remote mail server after end of data: 421 is listed on Cloudmark CSI-Global. 

host SMTP error from remote mail server after end of data: 421 is listed on Cloudmark CSI-Global. 

Best Answer

  • HT_GreenfieldHT_Greenfield Posts: 284 Contributor
    edited September 2022 Sep 13, 2022 Answer ✓

    According to, the - range of IP addresses is currently reassigned by LogicWeb Inc. to a VPN service provider, out of a larger range of IP addresses currently registered to LogicWeb. You'd have to contact your VPN service provider to address anything happening with your VPN service. I don't think Spectrum/Charter has anything to do with it.


  • LuisGonzalezLTLuisGonzalezLT Posts: 6 Spectator
    Sep 13, 2022

    It appears I need Spectrum tech support to go to the CLoudmark CSI IP Reputation Remediation Portal here:

    and submit the above IP addresses.

    Can I get tech support to do that, please?

  • LuisGonzalezLTLuisGonzalezLT Posts: 6 Spectator
    Sep 14, 2022

    Ah. I do see a VPN in this. Unloaded that and tried again. No reply back so far and nothing in the target email inbox. Guess I need to wait the few days until I get an error reply back and see what address that test went through :-(

  • LuisGonzalezLTLuisGonzalezLT Posts: 6 Spectator
    Sep 14, 2022

    I have added outlook.exe on this POC to tunnel areound the VPN and confirmed it does so by sending an email to an account in the same domain with and without the tunnel active.


    Received: from [] (port=50807 helo=PC1)

    WHOIS = LOGICWEB (this is the VPN provider)


    Received: from ([]:53356)\

    WHOIS = RRMA ( is the old roadrunner domain still in use by Spectrum) is only shoing up in a few blacklists so I sent some emails to various people. Still no joy :-(

  • LuisGonzalezLTLuisGonzalezLT Posts: 6 Spectator
    edited September 2022 Sep 14, 2022

    omg - so the problem ended up being completely unrelated to ip addresses.

    Turns out the source email domain did not have DKIM and SPF properly configured! Got that setup in the domains DNS and once that change propogated around mail began to be delivered once again.

    Just wanted to post that for anyone stumbling on this thread.

    Thanks all!

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