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anushahannaFlag for United States of America

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mail relay vs smtp

there is outgoing mail, but there is no service called smtp. the admin says mail relay is happening. what exactly does this mean?

thanks
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Jon Scriven
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The service is actually called Simple Mail Transfer Protocol.....
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i do not see "Simple Mail Transfer Protocol" in services.msc
Mail Relay means that the mail is being passed from your Exchange Server to the next server down the line.
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reijer
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Open a command prompt and type

net start smtpsvc

Open in new window


Let us know what happens....
Yes, probably should have clarified OS / Exchange version etc!
I use Exchange 2003 and so assumed! :S
This might be helpful if is is Exchange 2007 (or 2010)

http://technet.microsoft.com/en-us/library/aa998662.aspx
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>>Mail Relay means that the mail is being passed from your Exchange Server to the next server down the line.

so this does not have to have a service running?

In this particular machine, it is OS 2003 with exchange 2003.

So, in mail relay the same or different than SMTP?
C:\Documents and Settings\jimwe>net start smtpsvc
The service name is invalid.

More help is available by typing NET HELPMSG 2185.


C:\Documents and Settings\jimwe>
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Whether you are relaying mail or not, if there's no SMTP service running on the server, then Exchange isn't properly installed and cannot be working properly. Is it possible that the users in this company are sending mail using POP3 from their Outlook client without actually using an Exchange mailbox at all?
OK- sorry I did not ask the question more clearer..

there is outgoing mail (from the client box), but there is no service called smtp (in the client box). the admin says mail relay is happening, (and the client box will still be able to send emails out to the world). what exactly does this mean?

from what you are saying, it seems port 25 needs only be opened on the exchange server.

so, through what port is the client box able to send out emails?
i am only touching the client box and not the exchange box.
OK - well Small Business Server 2003 Exchange can be configured to use POP3, so this is probably how you have things configured.

http://www.msexchange.org/tutorials/Configuring-Incoming-Outgoing-Email-Windows-Small-Business-Server-2003.html
http://support.microsoft.com/kb/885685

I thought it still used SMTP to send outbound mail, but I might be wrong.  Either way you can look at the Connectors in System Manager (as outlined in figure 20 of the first link) and see.  If you are still confused, then take a screenshot of that and post it here.
OK - sorry - my post crossed.

Outlook connects to the Exchange server and it is only Exchange that needs SMTP.
Port 25 only needs to be open on Exchange if it is receiving maiol from external servers (if you are using POP3 only, then this wouldn't be the case).  Can't your admin give you the information you need?
Internally Outlook and Exchange communicate using RDP.

http://support.microsoft.com/kb/833799/
Why don't you tell us why you are asking these questions?  Then we might be able to give you clearer answers!
scriven_j, i was mistaken that the client machine should have port 25 open to send email. i believe i am wrong, after reading your posts.

i did 'telnet ipaddressofexchange 25' and it worked.

so in the above context, trying to understand 'mail relay', is just that the client machine is consider "in the world" and hence mail relay is happening, by post # 34909482

when the client machine is sending out an email, what port would it be using to send it out?
When you connect to an open port, the machine that is connecting will just open a random port for the response.  It is not really important and even a firewall should not block it, as it has been initiated from behind the firewall.

Your telnet command is connecting to Exchange in the same way as an external email server would do to relay mail items to your Exchange server, via Port 25, however RDP (which Outlook would use to communicate with Exchange) uses Port 135.

If you want to see what port your client is using, open a command window and type:-

netstat -na

Open in new window


This will show all the connections to ports (outbound and inbound).

Hope this is all clear?
If the output of Netstat is confusing, download and run TCPView and it should make things a bit clearer.

http://technet.microsoft.com/en-gb/sysinternals/bb897437

thanks - using tcpview on a client machine, i see outlook using 3000? here are sample 4 rows

Outlook.exe:3000    machinename:2383      exchangeserver1:5002           ESTABLISHED
Outlook.exe:3000    machinename:2381      exchangeserver2:5002           ESTABLISHED
Outlook.exe:3000    machinename:2377      exchangeserver3:5002           ESTABLISHED
Outlook.exe:3000    machinename:1121      exchangeserver4:1026           ESTABLISHED

how would you interpret this?
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I think the port numbers are the numbers after the machinename and the exchangeserver.

Once the machines are connected, they can change ports and this is normal (as you can see the machinename stepped up the sequence 2377, 2381, 2383 and will keep changing).

I don't see anything to be concerned about in what you have posted though.....
OK- i am getting it - If it is external address which outlook is sending email, then it is mail relay

why could i not see port 135 in TCPView? and what are the 3000/2383/5002 ports?
>>Once the machines are connected, they can change ports
so, originally it is 135 and then it can change?
In fact I think Outlook Anywhere uses ports 5000 - 5004.  Not sure about 1026, but I am not worried by what you have posted.
I am not an expert on Ports, but yes, they can change once the connection is established.
Thanks for all the helpful answers.. appreciate it.
Looks like your Exchange server has been configured to use Static Ports

http://objectmix.com/microsoft-exchange/278295-set-static-port-mappings-exchange-2003-server%3B-now-vpn-clients-cannot-use-outlook-xp-offsite.html

Exchange Information Store Interface Port = 5002
Apparently 1026 is the Calendar Access Protocol, so sounds like Outlook too!