question

NETWolF-2286 avatar image
0 Votes"
NETWolF-2286 asked NETWolF-2286 commented

Exchange 2016 stuck on send mails after port 25 has been block by my ISP

Good Morning everyone.

So I just noticed big queue in my mails to external servers. After fast investigate I noticed blocked port 25 here:
143851-2021-10-26-14-51-17.png

Fast call to my ISP and just got straight answer that my ISP block this port for security reason since last night.



So I started to looking for a solution - eg. change port to 587 and found some articles about that. In fact my mail server had used port 25 to send mail outside. I use command:

 Get-SendConnector | fl port

with bring: "Port : 25".

So my next step was change it to 587:

 Set-SendConnector "My.Domain.Name" -Port 587

And reboot.


Unfortunately I have still issue to send mail outside my exchange server. I receive that type of errors here:

2021-10-26T12:19:04.508Z,MyDomain.Name,08D9987A111B2A02,2,,142.250.115.26:587,*,,"Failed to connect. Winsock error code: 10060, Win32 error code: 10060, Destination domain: gmail.com, Error Message: A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond 142.250.115.26:587."


143847-2021-10-26-15-24-05.png



I rebooted server twice, also, flushed DNS cache.

office-exchange-server-administration
5 |1600 characters needed characters left characters exceeded

Up to 10 attachments (including images) can be used with a maximum of 3.0 MiB each and 30.0 MiB total.

AndyDavid avatar image
0 Votes"
AndyDavid answered NETWolF-2286 commented

The only thing I can think of is using a 3rd party SMTP service that you connect to as a smarthost ( typically on any port) and then they relay your messages on port 25 to external domains.

· 1
5 |1600 characters needed characters left characters exceeded

Up to 10 attachments (including images) can be used with a maximum of 3.0 MiB each and 30.0 MiB total.

Thanks for this suggest.

I started for now with complain to my ISP - let see what he respond...

0 Votes 0 ·
AndyDavid avatar image
0 Votes"
AndyDavid answered NETWolF-2286 edited

Port 587 is a client submittal port and typically requires the sending client to authenticate so that probably wont work.

You will need to get a static business level IP so your ISP wont block it.

· 1
5 |1600 characters needed characters left characters exceeded

Up to 10 attachments (including images) can be used with a maximum of 3.0 MiB each and 30.0 MiB total.

Thanks for your answer.

Unfortunately I don't have much choice to change my ISP - its only one provider in place where my server is :|

Nothing can be done here to fix this?

I have only static IP address with RevDNS,

0 Votes 0 ·