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Loss of SMTP services

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by admin-stuart 1 view

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Situation: Our LAN has one NT 4 SP6a server, same server runs Exchange Server 4. Exchange just runs intraoffice mail with default services. About 70 clients here mostly using Outlook 97 SP2, 3 or 4 old Exchange 5.0 clients, too.

Internet Mail on each client is set up to use our ISP's mail server (POP3) on other side of WAN and their firewall. As of yesterday noon, all of a sudden officewide we can't send (SMTP)Internet Mail (undeliverable messages). Still receive (POP3)just fine. Support at the ISP says problem with Outlook 97, needs upgraded to Outlook 98 at least due to documented problem(upgrade not available any longer as far as I can see). We set up Outlook Express on clients for Internet Mail, removed Internet Mail Services at each Outlook 97 client, now we can use Outlook Express just fine for Internet Mail.

What seems odd to me is that all Outlook 97 SP2 and Exch. 5.0 clients in this office lose ability to send SMTP mail at once because of software problem at the client, and can still receive from POP3 server. Why does Outlook Express work and the others not? Any suggestions as to direction to look are appreciated.

4 replies

by admin-stuart

P.S. Could our ISP's firewall configuration or a change in it allow SMTP traffic from Outlook Express while at the same time excluding traffic from OL97 and Exch. clients?

by mckaytech

To answer your question, yes, a change in either their firewall or in their mail server could result in this situation, particularly if they are using Exchange for their mail server. It's pretty certain that they either changed their firewall configuration or upgraded their server and it resulted in breaking your clients.

Microsoft has an interesting article on TechNet (Q218430) that describes the problem. It's related to the server expecting one security protocol and the client expecting another. Their suggestion is to upgrade to the Outlook2000 client but they do suggest a couple of workarounds if that is not feasible.

paul

by admin-stuart

I called my ISP, referred them to the same info you gave me, this morning outgoing email is back up here. They swear no changes have been made (they said they use Ipswitch's Imail) and seem close mouthed about all of it. Thanks for the help, Paul

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