Can you provide Netstat -an result and also check if in the Windows Firewall - Inbound Rule for Port 25 is allowed?
Exchange Server 2019 is blocking port 25?
I have setup a windows server 2022 with Exchange 2019 and am unable to send out email because outgoing port 25 is blocked.
I have done the following:
Stopped the firewall (Windows Defender) completely
Uninstalled virus protection
Updated the LAN driver to the latest Intel driver
Checked the OS several different ways for corruption
None of that has mattered.
NMAP shows that port 25 is open on the new server from my home office, but closed when I go from the new server to my home office Exchange Server.
Further, telnet testing shows I can connect to the new server from my home office but I can connect from the new server to my Home Office Exchange Server on port 25 nor to portquiz.net.
Can you think of any way or reason that Windows Server 2022 or Exchange Server could be blocking port 25? Or any other testing I could do?
Vultr.com says they have removed the default SMTP block from my account. They claim the port is open.
Thanks in advance for your help.
3 answers
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Jarvis Sun-MSFT 10,221 Reputation points Microsoft External Staff
2023-03-06T07:36:40.21+00:00 Hi @Craig M,
unable to send out email because outgoing port 25 is blocked.
Just wondering what makes you believe that the outgoing port 25 is blocked on your side?
Besides, could you run the get-messagetrackinglog cmdlet to check the mail flow on a failed message?
Get-TransportService|Get-MessageTrackingLog -MessageSubject <subject> -Sender <mailbox address> -Recipients <mailbox address> |ft timestamp,EventID,ClientHostname,ServerHostname,Source,ConnectorID -autosize
Such as:
Furthermore, to view the usage of Port 25, please try:
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- Open EMS with administrator in Exchange server, then run below cmdlet:
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netstat -aon|findstr "25"
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- Then run below command with PID to find the application, for example:
tasklist|findstr "1852"
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- At last please login EAC and locate to Receive Connector under Mail flow, open "Default FrontEnd <server name>", then double check the settings as below:
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Amit Singh 5,231 Reputation points
2023-03-06T14:36:10.2433333+00:00 Do you run Windows antivirus programs on Microsoft Exchange servers, you could follow this article to Check AV exclusion state. Can you send out mails? Have you ever updated windows?
You could try to restart server and check if this issue continues.
I found a similar thread for your reference.
Also check this article for more insight - https://www.alitajran.com/isp-blocks-smtp-port-25/