Solved

messages stuck in SMTP queue

Posted on 2004-09-18
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Last Modified: 2008-02-01
Here's the setup:
Dell Server running Windows Small Business Server 2003 with Exchange
Clients using Outlook 2003
SpeedStream 5200 DSL Modem/Router

Exchange is set up with an SMTP virtual server that was delivering all our external mail to the world with out incident.  Our original SpeedStream 5667 DSL Modem/Router failed and was replaced with the 5200.  All my outbound mail is stuck in the SMTP queue.  If I highlight one one of the entries in the queue it reports "Remote server did not respond to connection attempt"  From a command prompt on the server I have tried "telnet <smtp server name> 25" and I get "Connect fails".  This works from computers outside the office.  What would my next troubleshooting step or is there an easy fix.  I'm assigning high point value because I need to get this going by Monday.

Regards,

Jack Hess
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by:scampgb
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Hi jackhess,

It sounds like the new router isn't configured to allow the server to make an outbound connection on port 25.

Dependant on the configuration of the router, you'll have to explicitly specify that.

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by:scampgb
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I'm not familiar with the SpeedStream 5200, but I've found a web page that mentions the firewalling capability at  http://www.alltel.net/downloads/links/firewall

I notice that there's a "Server Ports" button in the config page - I'm guessing that this is where you'll need to look.

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by:jackhess
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Crap!  My bad.  The SpeedStream 5200 was the first replacement modem.  It had problems so the company then brought in the SpeedStream 5861 wihich is now in place.

Sorry,

Jack
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by:jackhess
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Also, on the 5861, I've turned the firewall off entirely.

Jack
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by:scampgb
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No worries.  You shouldn't have to turn off the firewalling capabilities entirely though, you probably just need to configure port 25 forwarding.

Do you have any other machines on your LAN (IE - behind the router)?  Can you try the telnet <smarthost> 25?

Just to be clear - the problem you're having is connecting to your ISP's smarthost from inside your network?
Alternatively, are you doing direct delivery?  In this case, do you have the problem with all emails or just some of them?

Incidentally, SMTP connectors are preferable to SMTP virtual servers.  Still, if it used to work :-)

Are you able to receive external mail to your Exchange server OK?
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by:jackhess
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My clients have two email accounts setup in their profiles the first default account is their Exchange account, the second is their account to the outside world.  Everyone is having the problem.  The outside account is configured as I would normally do it; name, password, SMTP server requires auth which is the same as the POP server, etc.  Since I didn't do anything originally with smarthost I didn't initially here either, though I have tried various combinations of smarthost and external DNS to try to get this thing moving.  Am I fundamentally on the right track here?  Or, do I need to rethink how I handle this combination of internal Exchange mail and external internet mail?

I'll find a machine behind the server and router and see if it telnets to the smtp server.
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by:scampgb
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Sorry, I'm a little confused about your setup now.  You're using Exchange just for Internal mail, and then your clients have a POP3 account with an ISP for external mail?

Or am I reading this wrong and your users have two accounts (an Internal and External one) on your Exchange server?
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by:jackhess
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In Outlook they have two accounts; one is the Exchange server account which is just internal mail.  The other account (setup in Outlook Email Accounts) is a POP/SMTP account.  I don't  know what the interaction is between Exchange server and the other account, except that when my clients do a send and receive any new messsages from their outside account is delivered to their Exchange mail box.  So I think the answer to your first question is yes.  Is that a valid configuration?

I got to a machiine behind the router tried the telnet test and it failed.
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by:scampgb
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It's a very unusual configuration...

Basically what's happening is that Outlook on your clients' PCs is fetching the email via POP3 and then storing it in their Exchange mailbox.

I don't quite understand why you've got it set up that way.  The better solution would be for the clients to have only one mailbox on the Exchange server and for the server to do the mail collection and sending.  Ideally you'd get the mail delivered to you by SMTP.

Advising on how best to move from your current position to that above will need us to understand a lot more about your setup, domain structure and mailboxes.

Anyway, back to your original question.  When your clients send emails:
They get sent to the Exchange server
The Exchange server then delivers the emails via SMTP, and does not use your ISPs SmartHost
Your Exchange server is failing to send these emails, and it's affecting all emails.

Does that sound right?
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by:jackhess
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On the button.

Can you suggest a good manual to configure a setup like you suggested?  That would make more sense, but everyone has their own login/password for their external email because it preexisted the Exchange server.  Their external email is hosted by a third party.  We don't want to get a static IP address and start doing their own hosting at this time.  So the situation is Exchange for internal communications with the ability to send to the outside world.

Is it too simple to say the root of the problem is that we can't establish a connection with our external smtp server?  And that the problem is below the Exchange server because we can't use telnet to make the connection either?
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by:scampgb
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Makes a bit more sense now :-)

Given that the problem started when you replaced the gateway (router), then I think it's a fair assumption that it's something to do with this.
If your Exchange server cannot contact the outside world on port 25, then it'll stop it being able to deliver mail.

I would guess that you'd have the same problem with inbound SMTP, but you don't use that at present.

I think that there might be some confusion when we're talking about telnetting to mail servers.  Have you always been trying to telnet to port 25 of the Exchange server, or an external SMTP server.
If you can't connect to port 25 of the Exchange server from an Internal PC, it means that there's something not correctly configured on Exchange.

Here's a test for you to do, from the Exchange server:
Look at one of the emails in the outbound SMTP queue on the Exchange server, check the recipient domain.  I'll assume the address is "me@example.com"

Go to a command prompt:
nslookup
set type=MX
example.com.
exit


This should then return you an IP address for the Mail Exchanger for that domain.  The Mail Exchanger (MX) is the mail server that receives email for that domain.  There may be several, so you'll want the one with the lowest "preference" number.

telnet [the IP address that you just found out] 25

This will connect you to the SMTP service on the domain-recipient's MX.  You should get a line like:
220 mailserver.example.com ESMTP Postfix

If you get a timeout with the telnet test, then it means your Exchange server can't contact that mail server for some reason.  This is likely to be a firewalling or routing issue.


As for explaining how to change the setup, I'll need to understand a lot more about what you've got at present.  Do all the users have one domain?  What exactly do the third-party provide in terms of mail hosting?

You don't need a static IP address in order to handle your own mail - and the Exchange server can be configured to pick up mail from a POP3 mailbox.
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by:jackhess
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Groovy.  I followed your example and looked at verizon.net, as I'm a user there.  It returned

Non-authoritaitive answer:
verizon.net    MX preference = 0, mail exchanger = relay.verizon.net

relay.verizon.net         internet address = 206.46.170.12

I telnet'ed using the above IP address and it choked.



As for the configuration change, is something explains the interactions of Exchange to the outside world in a simple fashion.  I'm imagining people behind an Exchange server who may want to hit there own personal email that is unrelated to the organization.  Typically, I'd just set up another Outlook email account to check that mail box and rock and roll.  The Exchange book I have makes it all sound very siimple, but something is gumming up my perspective.
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by:scampgb
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OK - from your test, it looks like the Exchange server can't contact external SMTP servers.  Can you web browse from the Exchange server?



There's an article at : http://searchexchange.techtarget.com/ateQuestionNResponse/0,289625,sid43_cid576802_tax295962,00.html that explains how to configure your Exchange SBS server to retrieve emails by POP3.
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by:jackhess
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Yes, I can browse without a problem.
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by:jackhess
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I've set up a user behind the SpeedStream with just POP/SMTP email, no Exchange, and I can't send.  I'm thinking this is now more a router/firewall problem than an Exchange problem.  Would it be appropriate to move this question to a different section?
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by:scampgb
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Ah - I think this is where we started off :-)

Just to check, your user inside the network that you've configured with an SMTP server: You are using an External SMTP server here, not your Exchange server?

I think it's an issue with the configuration of your SpeedStream.  I've done a few websearches, and the best I can find is a "Quick Start" manual, that's less than no use at all.

The website http://www.terrorist.net/webdocs/5861/ might give you a few hints, but I can't tell you exactly what you need to do as I can't see how it's currently configured.

Basically, you need to allow INBOUND traffic on port 25 to your Exchange server, and OUTBOUND traffic on port 25 to anywhere.
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by:jackhess
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Yes, indeed, full circle.  I found the terrorist.net doc and it had some ideas, but nothing that helped.  I'm going back to my DSL provider to see if they have any in-house expertise.  Which I doubt.
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scampgb earned 500 total points
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Do you have a copy of the manual for the SpeedStream?  If you've got it electronically and can put it on some webspace somewhere, I'd be happy to take a look at it for you.


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by:jackhess
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Well, the real problem was that my DSL provider will not allow any other SMTP server to be used on their circuit.  By setting up a Smarthost in Exchange and specifying their SMTP server, all went well.  Why these #$%@* couldn't have told me this last Friday is a question for them.  Why it worked using another SMTP server under the SpeedStream 5667 is also unknown.

scampqb you have been more than helpful and I thank you.  I'm giving you the points as I believe you alluded to this possibly being the problem.  I rejected that because all was well with the old router.
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by:scampgb
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jackhess,
Thanks for the points - glad I could help :-)

It's a great annoyance when there is more than one problem!

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