530 #5.7.0 Must issue a STARTTLS command first

Question

Dear Community,

we use an IIS 6.0 smtp-server running on a windows server 2012 r2 server as a mail-relay for sending emails direct to internet users. Unfortunately, with one mailserver it isn't working as expected. We getting the following errorcode, when a user from our side tries to send an e-mail to this partner/customer:

530 #5.7.0 Must issue a STARTTLS command first

The ssl-certificate is installed on the smtp-server and is working as expected.

Here is the log from the communication between our mailserver and the affected mailserver.

192.168.0.112, outlook.ourcompany.ch, 19.11.2020, 12:06:46, SMTPSVC1, MAIL02, 192.168.0.82, 0, 24, 209, 250, 0, EHLO, -, outlook.ourcompany.ch,
192.168.0.112, outlook.ourcompany.ch, 19.11.2020, 12:06:46, SMTPSVC1, MAIL02, 192.168.0.82, 0, 8, 0, 220, 0, STARTTLS, -, -,
192.168.0.112, outlook.ourcompany.ch, 19.11.2020, 12:06:46, SMTPSVC1, MAIL02, 192.168.0.82, 0, 8, 29, 220, 0, STARTTLS, -, -,
192.168.0.112, outlook.ourcompany.ch, 19.11.2020, 12:06:46, SMTPSVC1, MAIL02, 192.168.0.82, 0, 24, 245, 250, 0, EHLO, -, outlook.ourcompany.ch,
192.168.0.112, outlook.ourcompany.ch, 19.11.2020, 12:06:46, SMTPSVC1, MAIL02, 192.168.0.82, 16, 47, 117, 250, 0, MAIL, -, FROM:<My.Name@ourcompany.ch>,
192.168.0.112, outlook.ourcompany.ch, 19.11.2020, 12:06:46, SMTPSVC1, MAIL02, 192.168.0.82, 0, 27, 85, 250, 0, RCPT, -, TO:<info@ourcustomer.ch>,
192.168.0.112, outlook.ourcompany.ch, 19.11.2020, 12:06:46, SMTPSVC1, MAIL02, 192.168.0.82, 31, 19350, 149, 250, 0, BDAT, -, <7a82bece7c6941c2a0c56cf665e81bb2@ourcompany.ch>,
192.168.0.112, outlook.ourcompany.ch, 19.11.2020, 12:06:46, SMTPSVC1, MAIL02, 192.168.0.82, 0, 4, 133, 240, 63, QUIT, -, outlook.ourcompany.ch,
194.147.x.x, OutboundConnectionResponse, 19.11.2020, 12:06:46, SMTPSVC1, MAIL02, -, 15, 0, 20, 0, 0, -, -, 220 mail.ourcustomer.ch ESMTP,
194.147.x.x, OutboundConnectionCommand, 19.11.2020, 12:06:46, SMTPSVC1, MAIL02, -, 15, 0, 4, 0, 0, EHLO, -, mail.ourcompany.ch,
194.147.x.x, OutboundConnectionResponse, 19.11.2020, 12:06:46, SMTPSVC1, MAIL02, -, 15, 0, 14, 0, 0, -, -, 250-mail.ourcustomer.ch,
194.147.x.x, OutboundConnectionCommand, 19.11.2020, 12:06:46, SMTPSVC1, MAIL02, -, 47, 0, 4, 0, 0, MAIL, -, FROM:<My.Name@ourcompany.ch> SIZE=19633,
194.147.x.x, OutboundConnectionResponse, 19.11.2020, 12:06:46, SMTPSVC1, MAIL02, -, 47, 0, 46, 0, 0, -, -, 530 #5.7.0 Must issue a STARTTLS command first,
194.147.x.x, OutboundConnectionCommand, 19.11.2020, 12:06:46, SMTPSVC1, MAIL02, -, 62, 0, 4, 0, 0, QUIT, -, -,

I'm pleased for every input to solve this issue.

Thanky you and best regards,
Lucian

Answer 1

Hi Lucian,

Seems that your issue is more related with IIS, please create a thread in IIS forum to check if they have any hints about this issue.

As your issue is out of our Windows Server & Client support scope, please allow me to change the tag to not support.

If my redirection to IIS forum is useful for you, please accept the reply as answer so that other customers could find the right place to ask.

Bests,

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