Slow inbound mail from Internet to Exchange 2019

Question

Our server does not want to accept mail from the outside, or rather, it does, but for a very long time. The provider's PTR record has been created and is correct. But the server name, as we determined in the test, does not match the domain name of the mail server. - Outwardly it looks like mail3.domain.kz, and inside like srv-ts-exch01.ADdomain .local, I have already changed it everywhere where possible. But online testing services still don’t see the name match.

Answer 1

Hello @Карен Читян,

According to your description, “Our server does not want to accept mail from the outside, or rather, it does, but for a very long time”. I would like to confirm with you that you mean that users within the organization cannot receive mail from the outside or is it that it takes a long time to receive an email from an outside party?

If so, will the external sender receive the NDR? In addition, it is recommended that you use Get-messagetrackinglog to check whether there is information about related emails to ensure whether the emails have entered the organization. Besides, could you see the stuck emails in the Queue Viewer? For those external emails that can be received, you can check the message headers using Message Header Analyzer: https://mha.azurewebsites.net/ and see if you can find any more clues about the delay.

---

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

Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.