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Intermittent problems sending POP3 email via Outlook

itplatoon
itplatoon used Ask the Experts™
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A few months ago, a SBS 2003 server was migrated to a new SBS 2011 server. Since then there have been intermittent problems where email message will queue up in the Outlook outbox and not send out as expected. recently, only 2 people had the issue where another 6 people had no issues. Email is hosted by a 3rd party and accessed via POP3. The internal exchange server is not used. An old SBS 2003 server was recently migrated toa  new SBS 2011 server. The outbound email problems began after the new SBS 2011 was brought online. The site has a 24 port ethernet switch and a watchguard firewall. Most of the time, all of the email flows as expected but sometimes, email just gets clogged up in the outbox and then will resume sending later in the day or the next day. We have tried used both the ISP SMTP server and the POP3 providers SMTP server and this does not seem to affect the problem. I have not been able to find anything in the event logs either.
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Top Expert 2013

Commented:
Sending is via SMTP not POP, so it is probably an issue with the Outlook not resolving the SMTP server name or not authenticationg. Not authenticating is probably not the isseue since it eventually sends.

How is DNS configured?
The SBS should have ONLY it's own IP in its NIC configuration under DNS.
The SBS by default uses root hints, but there have been some issues with that lately, so I would recomend adding forwarders in the DNS management console with the ISP's DNS server's IPs if you have not already done so.
The PC's should point ONLY to the SBS's IP for DNS.

If the above is configured correctly I would recomend changing DNS servers used, perhaps try Google's which are public and 8.8.8.8 and 8.8.4.4

Author

Commented:
I double checked the TCPIP settings for the server's only NIC and they are correct; I added teh 2 google DNS servers as forwarder #3, #4. We'll see if this helps.
Top Expert 2013

Commented:
I find Windows doesn't always work as it should switchng to second and third DNS forwarders, you might want to try making one of the Google DNS servers as primary (top of the list) as a test.

Author

Commented:
That is good advice. I have seen that behavior too on windows systems, where the 2nd or 3rd DNS server is not invoked when the 1st DNS server is not responding. I set the 2nd google server as #1 on the Forwarder list.

Author

Commented:
This problem is still ongoing. The problem happened to a few of the people in the office today but not everyone. One of the users got the following message in Outlook: Relaying denied. IP name possible forged (1.1.1.1) where 1.1.1.1 is the IP address assigned to the firewall.
Top Expert 2013

Commented:
If they receive a relaying message it means they did connect to the service provider's mail server but it was rejected. Either it is the wrong server address, or they need to use authentication under the "more settings" option of the e-mail account configuration.

Might be more of an issue to take up with the service provider.

Author

Commented:
After further research, here is a possible culprit:

The IP address of the firewall is: 1.1.1.1

The following A record was setup back in January:

Remote.mycompany.com
1.1.1.1

NSlookup of this IP address provides the following:

name:    1-1-1-1.acme.acmemail.net
Address:  1.1.1.1.

So the forward and reverse IP addresses do not match.
This company has email hosted with a 3rd party which is not the ISP providing their internet access.
Top Expert 2013

Commented:
Reverse IP addresses do not matter when you are sneding e-mail through Outlook to a 3rd party.

By service provider earlier I did not mean ISP, but you could use their SMTP server for sending.

Reverse IP only has to be in place if you are not sending through an ISP or 3rd party, such as using exchange. also the revese IP is not set up in your public DNS records, it is set up by your ISP.
After further review and calls to the ISP, it turns out that the ISP was having some SMTP mail server issues where it would reject inbound email and the error that we reported was seen by other customers. The ISP created some custom SMTP settings in order to work around the problem.

Author

Commented:
I figured out the root cause of the problem by opening a ticket with the ISP.