Developer required to build email function

We require an email function to be developed for us. The function will receive a request from an iphone app (using JSON) which it will process, then prepare an email response which it will send out. All of this needs to be reported along with a function to resend any emails.

We're looking for a developer that can show they have the skills to create this function to the specifications below. We would like to start the project as soon as the right person for the job is found.

A full breakdown of the requirements is below. Please feel free to send over any queries but i've tried to provide a thorough description of the job and provided any technical information

We have a windows and linux VPS server with godaddy which we will provide you access to in order to transfer the function over to our platforms.

An iphone app will send a JSON request to a page on our server (to be created as part of this job and details to be provided to the app developer). Variables being passed on by the app in the JSON request are below.

- Username and password - this will be passed on via the app to authenticate the request
- VersionID
- ContentID
- Email To (aka email1)
- Email From (aka email2) - optional
- Message - optional
- UserID

There will be two different types of emails. One for when email1 is present and when when both email1 and email2 are present. Email1 is a pre-format html email sent to the email address in the JSON request along with an attachment as determined by the contentID (eg.contentID.doc - these files will be made available in a folder stored on the server) and from our own email account (eg. contact@ourdomain.com). If Email1 and Email2 is present then a different pre-formatted html email is sent to the email1 address along with the contentID attachment, but this time the from field of the email shows up as Email2.

Basically, email1 only function is when a user requests the requested attachment to themselves. email1 and 2 function is used when the user is sending the requested attachment to their friend as a gift.

I believe for this function an email platform would need to be installed on our server as the emails will be using this to be generated and sent out rather than an email provider such as google apps or the godaddy email function. Will probably use an opensource platform to keep costs down, but will consider licensing a platform on developers advise. We would also take the developers advice on security issues.

The email platform needs to be reliable and scaleable so it can handle 100 emails an hour or a minute. If this limitation is based on the VPS configuration then we can simply upgrade our godaddy account to a more powerful VPS or we can migrate to another more powerful server as required.

The function will need to respond to the JSON request to tell it that everything has been received ok and processed correctly, or if there is a problem with the variables or processing them, etc.

Reporting - All variables provided in the request will be stored in a table (probably in an sql database) and allocated a unique "request ID". All other functions (such as date/time stamp of the request being received and the email being sent) will be added to this table/database too. We'll need to be able to view all requests in a report, which we can narrow down by date and search by to/from email address.

Re-send - We'll nee to be able to resend any request just by clicking a button from the reporting tool.

Custom send - i guess when building the service, to test it, we'll need a simple form which can have all of the variables above, and this form will make spoof request to the service (and flag it in the database as a custom send).

Thanks for your time to read this job posting, and good luck with your bids.