Question : We can receive but not send email, ISP blames it on microsoft exchange server

We run a small (8 workstation) network with Windows NT 4, Small Business Server. We run Microsoft Exchange for our "internal" email. Our "external" email is through Nuvox (provides bundled voice and data over a partial T1) Last Friday, without any known changes to our system, addressees of external email stopped receiving emails. We run Outlook 2000 on all but one workstation. Each workstation is configured to use pop.nuvox.net as incoming mail server and smtp.nuvox.net as outgoing mail server. We can send and receive internal emails but can only receive external emails. When we send emails they go to sent items folder. Most workstations have Norton antivirus running with email scanning. When the system is operating properly the norton scanning message pops up when an external email is sent. That is not happening now. I have removed and reinstalled the internet email service on a workstation - no change. We have rebooted the server running Microsoft Exchange - no change. In discussing with Nuvox, they tell me no sent emails from our domain are logged on their smtp server all last week - a period of time during which the system was working properly. Based on this, they tell me Microsoft Exchange is actually sending our external email not their smtp server. I don't know how to check this, and I don't know what could have happened between Thursday and Friday to cause this. Ideas?

Answer : We can receive but not send email, ISP blames it on microsoft exchange server

Hi,

Normally, if your Exchange Server starts sending these mails, you should need to reconfigure your Outlook client, to either MAPI (Exchange Server Setting) or the pop3 or SMTP server should be changed to your Exchange Server, else the Exchange server does not do this.. Do you have multiple Outlook settings to collect mail?? If you sue pop.nuvox.net and smtp.nuvox.net, then why are u using your mailserver?? Do these ip addresses point to your internal mail server?? Else, this mail server doesn't have any function at all (for as far as i can see)..

If mails don't get send but you can recieve them, then my guess os that the sending machine (the nuvox i guess) has a DNS resolvance problem.. How is DNS configured on your mail sending server?? WIth forwarders??