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we have two internet provider (Main link and backup link) when we switched for the second ISP internet provide we does not receive external email and i am listing down the dedicated environment
Exchange 2016
Mail Gateway
Public DNS
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Hi @Bebo Edward ,
Did the problem occur after you changed your ISP?
Did the external sender receive an NDR after sending it failed?
First, please contact your ISP and check whether your DNS records are set correctly, including MX records and A records.Please make sure to point to the correct Exchange server.
Check your firewall settings, whether the necessary ports are opened, and SMTP communication can pass smoothly.
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Hi @Bebo Edward ,
Do suggestions above help? If the issue has been resolved, please click “Accept as answer” to mark helpful reply as an answer, this will make answer searching in the forum easier and be beneficial to other community members as well.
Thanks for your understanding.
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Hi @Bebo Edward ,
I am writing here to confirm with you how thing going now? If the above suggestion helps, please click “Accept as answer” to mark helpful reply as an answer.Your action would be helpful to other users who encounter the same issue and read this thread.
Thanks for your understanding.
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