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Cannot send/receive emails outside domain after cable modem replaced RRS feed

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    Spectrum replaced the modem for our office yesterday and gave us a new range of public IP addresses. We were able to get most of our internet traffic working again, but we're having problems emailing in and out of the office - only internal emails deliver smoothly.

    We've updated our 1:1 NAT settings on our firewall and the https://testconnectivity.microsoft.com passes, but there are a few certificate warnings. Our mobile devices and webmail (mobile apps and mail.contoso.com) cannot connect at all. http://mail.contoso.com will ping from the outside, but https://mail.contoso.com will not.

    Do we need to change anything on the Exchange server - like certificate settings - or is there something we missed on the network equipment settings? All other internet traffic is working properly.

    Thanks,

    J. J.


    • Edited by Zepfanman Wednesday, August 9, 2017 5:22 PM typo
    Wednesday, August 9, 2017 5:17 PM

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    It looks like DNS settings are finally working since there is an approximate 24 hour window to propagate across the internet, so I think this is resolved now.

    We did notice that the IP address that Spectrum gave us is on a spam block list, though! So now we're trying to resolve that problem - we can receive emails from the outside, but can't send to a lot of agencies.

    • Marked as answer by Zepfanman Wednesday, August 9, 2017 6:43 PM
    Wednesday, August 9, 2017 6:42 PM

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    Hi Zepfanman 

    Have you checked the exchange mail queue for errors. If you have exchange 2010 it will be under tools and queue viewer this will tell you if mails are getting stuck going outbound. If Exchange 2016 you can use powershell command. 

    Get-Queue
Get-Queue -Identity "QueueName" | Get-Message | fl

    If mail flow is not working inbound it could be a firewall rule or wrong public IP address is assinged to the MX record. If you telnet to mail.contoso.com does the exchange server respond.    


    If you find that my post has answered your question, please mark it as the answer. If you find my post to be helpful in anyway, please click vote as helpful.



    Wednesday, August 9, 2017 5:52 PM
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    It looks like DNS settings are finally working since there is an approximate 24 hour window to propagate across the internet, so I think this is resolved now.

    We did notice that the IP address that Spectrum gave us is on a spam block list, though! So now we're trying to resolve that problem - we can receive emails from the outside, but can't send to a lot of agencies.

    • Marked as answer by Zepfanman Wednesday, August 9, 2017 6:43 PM
    Wednesday, August 9, 2017 6:42 PM