IIS SMTP Server used for relay purpose, launch smtpsvc event with code 4006, the remote host dropped the connection.

Question

IIS SMTP Server used for relay purpose, launch smtpsvc event with code 4006, the remote host dropped the connection.

From these SMTP I can stablish comunication with the remote host, via openSSL on port 465 and complete all the process to send a mail.

However, I've analized, SMTP server comunications capturing packets, at the server and the firewalls, and I can see the same behavior.

SMTP Sever start the comunication, send a SYN, remote host respond with SYN-ACK, before SMTP Server send ACK again, and it does nothing, the server SMTP doesn't try to send anything. Before 60 seconds, remote host drop the connection, sending a RST, ACK.

Why SMTP relay doen't try to do anything?

The server resolves well the smart host's name, and It can stablish connection perfectly (how I can do with the OpenSSL in the same server)

Any Ideas, about this Issue?

Answer 1

@RGERSOL

Make sure you have allow the machine to relay, if not you could try to set the relay setting:

Open IIS Manager > Properties > Access tab > Relay Restrictions. Also, try to turn off the firewall.

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Answer 2

Comunications OK.

Access restrictions OK, We permit all conections, anonymous port 25 for test, in a futere we will apply restrictions.

Relay restrinctions, we permite any could to send mails to be relayed.

Delivery>

Outbound Security> Basic Autentication, with TLS cipher

Outbound connections, without limits, and port 465

Advanced Options> hops 35 (It was 15, but we elevate it for a test purposes), Complete name's domain, configured with the domain

When the service start, smtpsvc connect, OK, but does nothing, and the remote host, reset before wait 60 seconds.

How it's possible that a server software, a service, don't show any logs, any trace about the actions with mails queued?