Build a List Management Software

We are looking for a developer with specializations in PHP who has experience with email marketing softwares. We are looking to build our own in house email marketing list management software that will be able to send out a large amount of email campaigns concurrently. We are a small ESP servicing multiple clients, and we are using a hybrid system at the moment (we've built our own server architecture, but using a third party list management software). We are looking to build something similar to Mailchimp, but with different features integrated. We do have a portion of the software in development already, so you will be communicating with some of our in house developers. Some of the main features of this SAAS (software as a service) will include: - Software that will be hosted in our own website - Multiple User accounts - API (for content upload, data upload and download with compatibility to multiple platforms) - Ability to display server logs in relation to the specific IP's associated to the user account - Campaign Email Stats display - Email campaign creator - Ability to create and send out the following types of emails: --> Transactional --> Triggered --> Auto responder --> Marketing/Newsletter type - Ability to create dynamic content tags/Custom Fields - Ability to create email preference centre forms and modify user lists based on preference settings All these different features should be created on a modular basis Admin panel (CMS) for the software, which will allow us to manage the software. Documentation for the software will be required to be written. We do have the majority of the requirements available upon demand.