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We're using IIS 6.0 SMTP Virtual Server to receive and forward e-mails from our website hosted on the same dedicated machine. Everything worked fine, up until we recently transfered the e-mail service to Online.net (that also hosts our dedicated web server) on a Cloud based service. I updated the Smart Host in IIS SMTP server to smtp.cloud.online.net, as well as the Authentication. Problem is messages sent from our website arrive to the mail server as they used to but got stuck in the Queue folder.

The Logs do not mention any particular error, but strange enough they never go further, to the Authentication process. Here is an exemple:

212.47.233.113, OutboundConnectionResponse, 29/10/2017, 18:17:24, SMTPSVC1, MUSIQUE, -, 0, 0, 28, 0, 0, -, -, 220 23a72c26dae0 ESMTP ready,
212.47.233.113, OutboundConnectionCommand, 29/10/2017, 18:17:24, SMTPSVC1, MUSIQUE, -, 0, 0, 4, 0, 0, EHLO, -, MUSIQUE,
212.47.233.113, OutboundConnectionResponse, 29/10/2017, 18:17:24, SMTPSVC1, MUSIQUE, -, 0, 0, 16, 0, 0, -, -, 250-23a72c26dae0,

When switching back to the former SMTP Smart Host server and Authentication credentials, the messages are sent fine. Here is an exemple of the Logs from a proper transaction:

217.76.129.126, OutboundConnectionResponse, 31/10/2017, 11:51:11, SMTPSVC1, MUSIQUE, -, 63, 0, 41, 0, 0, -, -, 220 smtp-02.serveursdns.net ESMTP Postfix,
217.76.129.126, OutboundConnectionCommand, 31/10/2017, 11:51:11, SMTPSVC1, MUSIQUE, -, 63, 0, 4, 0, 0, EHLO, -, MUSIQUE,
217.76.129.126, OutboundConnectionResponse, 31/10/2017, 11:51:11, SMTPSVC1, MUSIQUE, -, 94, 0, 31, 0, 0, -, -, 250-flse665-a15.serveursdns.net,
217.76.129.126, OutboundConnectionCommand, 31/10/2017, 11:51:11, SMTPSVC1, MUSIQUE, -, 94, 0, 8, 0, 0, STARTTLS, -, -,
217.76.129.126, OutboundConnectionResponse, 31/10/2017, 11:51:11, SMTPSVC1, MUSIQUE, -, 141, 0, 28, 0, 0, -, -, 220 2.0.0 Ready to start TLS,
217.76.129.126, OutboundConnectionCommand, 31/10/2017, 11:51:11, SMTPSVC1, MUSIQUE, -, 219, 0, 4, 0, 0, EHLO, -, MUSIQUE,
217.76.129.126, OutboundConnectionResponse, 31/10/2017, 11:51:11, SMTPSVC1, MUSIQUE, -, 266, 0, 31, 0, 0, -, -, 250-flse665-a15.serveursdns.net,
217.76.129.126, OutboundConnectionCommand, 31/10/2017, 11:51:11, SMTPSVC1, MUSIQUE, -, 266, 0, 4, 0, 0, AUTH, -, -,
217.76.129.126, OutboundConnectionResponse, 31/10/2017, 11:51:11, SMTPSVC1, MUSIQUE, -, 297, 0, 16, 0, 0, -, -, 334 UGFzc3dvcmQ6,
217.76.129.126, OutboundConnectionResponse, 31/10/2017, 11:51:11, SMTPSVC1, MUSIQUE, -, 344, 0, 35, 0, 0, -, -, 235 2.7.0 Authentication successful,
217.76.129.126, OutboundConnectionCommand, 31/10/2017, 11:51:11, SMTPSVC1, MUSIQUE, -, 344, 0, 4, 0, 0, MAIL, -, FROM: SIZE=3211,
217.76.129.126, OutboundConnectionResponse, 31/10/2017, 11:51:11, SMTPSVC1, MUSIQUE, -, 375, 0, 12, 0, 0, -, -, 250 2.1.0 Ok,
217.76.129.126, OutboundConnectionCommand, 31/10/2017, 11:51:11, SMTPSVC1, MUSIQUE, -, 375, 0, 4, 0, 0, RCPT, -, TO:,
217.76.129.126, OutboundConnectionResponse, 31/10/2017, 11:51:11, SMTPSVC1, MUSIQUE, -, 422, 0, 12, 0, 0, -, -, 250 2.1.5 Ok,
217.76.129.126, OutboundConnectionCommand, 31/10/2017, 11:51:11, SMTPSVC1, MUSIQUE, -, 422, 0, 4, 0, 0, DATA, -, -,
217.76.129.126, OutboundConnectionResponse, 31/10/2017, 11:51:11, SMTPSVC1, MUSIQUE, -, 468, 0, 35, 0, 0, -, -, 354 End data with .,
217.76.129.126, OutboundConnectionResponse, 31/10/2017, 11:51:11, SMTPSVC1, MUSIQUE, -, 531, 0, 34, 0, 0, -, -, 250 2.0.0 Ok: queued as 1FA3620CD4,
217.76.129.126, OutboundConnectionCommand, 31/10/2017, 11:51:11, SMTPSVC1, MUSIQUE, -, 531, 0, 4, 0, 0, QUIT, -, -,
217.76.129.126, OutboundConnectionResponse, 31/10/2017, 11:51:11, SMTPSVC1, MUSIQUE, -, 562, 0, 13, 0, 0, -, -, 221 2.0.0 Bye,

Anyone has a clue why the new SMTP server smtp.cloud.online.net do not ask for (or do not accept) authentication from our IIS SMTP server? Everything works fine when using the same server and credentials on Outlook.

Many thanks,

Andrei


Thanks for your reply @Finny. The OS on the machine is Windows Server 2008 r2 with IIS 7.5. But the SMTP virtual server Windows provideds with this plateform is 6.0. Yes, outbound problem only. As stated, the messages sent from the website, arrive to IIS 6 SMTP, but are not delivered through the new Smart Host smtp.clould.online.net. They got stuck in the Queue folder. Yes, basic authentication (email + password). Tried both with TLS on Port 587 and without TLS on Port 25. But as stated, it's not an really authentication issue. Problem is contrary to what was happening when using the former SMTP Smart Host (or even smtp.gmail.com, which works as well), the new Smart Host smtp.clould.online.net doesn't even ask for authentication. Please check the logs provided. Best, Andrei

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First, IIS 6 will be 2003 and I would be remiss if I didn't advise you to migrate away from an OS that is no longer patched or supported.

So this is an outbound problem only, correct? I'm not sure if you are saying the emails go from the website (also at Online.net) > IIS 6 SMTP > back to Online.net, or if the website and IIS 6 SMTP are on the same host > Online.net.

How do you have your outbound security set? Basic authentication? Is TLS required? These are on the properties of the SMTP virtual server, delivery tab.

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