(This sounds like you want to implement a feature like craigslist).
The IIS SMTP service can send email, and also accept email.
Here is what you want to do.
Configure your IIS SMTP service to accept emails for a domain (You can configure this in the properties of the IIS SMTP service, under domains). Say domain name "myserver.example.com"
Then, in your DNS server, configure a MX record that points to "myserver.example.com".
Now, when email gets sent to your IIS SMTP server, it will actually get placed in your mailroot/drop folder (you can also change this folder in the IIS SMTP Service properties).
Now that you are accepting email, the next step is to write a script that will:
1)Parse the emails.
2)Modify them accordingly (do you just want to change the "to" address?).
3)If you want to resend the emails, then you need to modify them accordingly.
You will need to add a single X-Sender header, that is used to identify the email address sending the email, and a X-Receiver header, for each recipient that is going to accept the email. Here is an example email that was modified:
X-Sender: [email protected]
X-Receiver: [email protected]
X-Receiver: [email protected]
From: "jim bob" <[email protected]>
To: <[email protected]>
Subject: test
MIME-Version: 1.0
Content-Type: text/plain;
Message-ID: <024f01c9e130$b3eca500$0401a8c0@local>
test
Once you have this modified content, you will want to write it to a file in the mailroot/pickup directory. Be sure to use a unique name.
The IIS SMTP Service will come by, pickup the email, and relay it on, sending the email using the X-Sender as the MAIL FROM address, and sending it to each email address listed in each X-Receiver header.
4)Run this script as a scheduled task. Another option is to build it as a windows service, or to implement something like a filesystemwatcher, where it executes each time an email is created as a file.
5)Another option to all of this is to actually implement a SMTP Event Sink, but I think that is overkill for what you want to do, and can create more headaches, than it solves. I would only go the event sink route if I like pain.
Hopefully I didn't make that about as clear as mud.
