Need a fix on why I can't send Exchange email to Yahoo users

Ahmad Dhamiri Muhammad Farhan 20 Reputation points

Hi everyone,

I'm having an issue where my email server (Exchange Server 2016 on-prem) can't send to Yahoo Mail users.

Before I made this question, I have done several troubleshooting's to our email server, where first we restart the Exchange Server service, but that's only proven as temporary solution. Next what I did was to change the SPF and the DKIM configuration. After checking with mail tester website, it seems our DKIM and SPF for our email server are okay after change, but we still can't send emails and attachments to Yahoo Mail users.

After further investigating, it's related to DNS, more likely due to Yahoo couldn't find our mail checker (IMSVA) server's A record, and I reached to other people that they mentioned that the ISP needs to delegate the IP provided by them to our gateway. Is that correct? Or we can do something about this to mitigate this issue?

Exchange Server Management
Exchange Server Management
Exchange Server: A family of Microsoft client/server messaging and collaboration software.Management: The act or process of organizing, handling, directing or controlling something.
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  1. JimmyYang-MSFT 48,551 Reputation points Microsoft Vendor

    Hi @Ahmad Dhamiri Muhammad Farhan

    Based on your description, it seems you could not send the email to Yahoo users. In this way, we recommend you check the following aspects:

    1)please kindly check if set up SPF, DKIM and DMARC for your custom domain in Microsoft 365 completely. Please also make sure if your network bypassed Office 365 URLs and IP address ranges which help to deliver email to Yahoo account.

    2)If this issue only happened when you send email to Yahoo account. This issue may be caused by that Yahoo had identified Microsoft as "abusive”. This is the issue between Yahoo and Microsoft, instead of your issue.You could contact Microsoft Support to report this issue: Get support - Microsoft 365 admin | Microsoft Learn

    If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".

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  1. Ahmad Dhamiri Muhammad Farhan 20 Reputation points

    Hi Jimmy,

    1. I believe the server doesn't associate with Microsoft 365 as it's an in-house domain, if I can say that. Haven't checked if our network bypassed the office 365 URL and IP address ranges but will check it out from time to time.
    2. It may be due to our last Public IP address reported by Yahoo as abusive, although not enough evidence to proof so. After our network migration, we have reached to our ISP provider to delegate the public IP address they gave us to resolve the issue. After quick troubleshooting, we managed to email to Yahoo users within 3 days at least.

    Thanks for the help, Jimmy.

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