Sending emails using IIS 6.0 SMTP service without using a relay

Question

I am running Windows server 2008 R2 Enterprise with IIS 7.5 & 6.0 and the SMTP service enabled. Following this guide, the SMTP service was installed and configured to relay outbound emails via my personal gmail account:

IIS 6.0 (SMTP Virtual server #1)

• outbound security: basic authentication ([email protected] + password) + TLS encryption
• outbound connections: TCP port=587
• advanced: Smart host = smtp.gmail.com

IIS 7.5 (SMTP E-mail)

• E-mail address: [email protected]
• SMTP Server: smtp.gmail.com
• Port: 587
• Specify credentials: [email protected] + password

When I make a test with telnet:

220 SERVER Microsoft ESMTP MAIL Service, Version: 7.5.7601.17514 ready
ehlo
250-SERVER Hello [172.29.40.7]
250-TURN
250-SIZE 2097152
250-ETRN
250-PIPELINING
250-DSN
250-ENHANCEDSTATUSCODES
250-8bitmime
250-BINARYMIME
250-CHUNKING
250-VRFY
250 OK
mail from:[email protected]
250 2.1.0 [email protected] OK
rcpt to:[email protected]
250 2.1.5 [email protected]
Data
354 Start mail input; end with <CRLF>.<CRLF>
Subject:Test subject

This is the email body

.
250 2.6.0 <SERVER> Queued mail for delivery

It does work but here is what I get in Gmail:

Return-Path: <[email protected]>
Received: from SERVER
        by mx.google.com with ESMTPS id g9sm9663174wix.1.2013.04.17.06.20.48
        (version=TLSv1 cipher=RC4-SHA bits=128/128);
        Wed, 17 Apr 2013 06:20:49 -0700 (PDT)
Received: from  ([127.0.0.1]) by SERVER with Microsoft SMTPSVC(7.5.7601.17514);
     Wed, 17 Apr 2013 15:03:07 +0200
Subject: Subject:Test subject
From: [email protected]
Bcc: 
Return-Path: [email protected]
Message-ID: <0000000a@SERVER>
X-OriginalArrivalTime: 17 Apr 2013 13:03:16.0990
Date: Wed, 17 Apr 2013 06:20:49 -0700 (PDT)

This is the email body

As you can see there are a several issues:

• the destination email ([email protected]) has become the source and the 1st return path
• there is no destination email anymore
• what I had setup as a source ([email protected]) is only present in the 2nd return path

Q1: Is someone able to explain why that is?

Also, I read on Google forums that there is a 500 emails / day limit which means that even I manage to fix the above problems it still won't be good enough as I need to send more emails than that.

Q2: Is there a way (with or without IIS SMTP) to get the server to send emails directly to whatever the destination email address without going through a relay ?

Solution 1

354 Start mail input; end with <CRLF>.<CRLF>
Subject:Test subject
...

should be

...
354 Start mail input; end with <CRLF>.<CRLF>
From: [email protected]
To: [email protected]
Subject:Test subject
...

If you don't add the From: text gmail will add From: [email protected] To: should also be added to follow the standard way of SMTP.

Solution 2

Q2: Is there a way (with or without IIS SMTP) to get the server to send emails directly to whatever the destination email address without going through a relay ?

A: Yes. Create a remote domain for each gTLD you want to send email to and remove the forwarding configuration. SMTP will then use DNS to locate the email servers for those remote domains and will deliver email directly to those remote domains.

For instance, if you want to send email to any .com email address then create a remote domain for *.com. Do likewise for any other gTLD that you want to send email to.