take PHP-based autoresponder to completion

Greetings, We've done a bit of PHP code on an autoresponder, but we need help to get it finished while we work on another piece of this much larger project at the same time. What we have (all written in PHP with HTML/javascript at the front-end): * A MySQL database that receives email signups from our various web forms. * the code to send single emails from a system set up to fulfill PDF requests. * some of the code required to send emails in a pre-programmed/scheduled sequence. This system will live on a Linux VPS that I will give you ssh access to. You should understand cron if you want to work on this project. INTEGRATION: This system will be sending the emails through SendGrid using their Web API. The documentation is here: [login to view URL] THE PROJECT - what needs completing: * When a user submits their email address, they will not only get the specified PDF, but also be assigned to a related email sequence -- we call them "threads". The first email in the thread will be sent to the user immediately. * Each subsequent email in the series needs to be sent a certain number of days (specified by an administrator) after the last email (e.g. email2 is sent 3 days after email1; email3 is sent 5 days after email2; ...). When no more emails are left in the sequence, the thread is complete. * Each email in a thread should be stored in plaintext on the filesystem, OR as "blob" text in the database (whichever you find more reasonable for this project). * Emails will contain template features (such as {{name}} for the subscriber's name) that must be processed (filled in) before the email is sent to SendGrid. * We also need an automatic unsubscribe facility, the URI of which needs to be automatically inserted into the email. Unsubscribing means removal of this email address from that sequence (but not from our database). The date that the sequence was terminated should be recorded. * Emails should be sent with the minimum number of API accesses to SendGrid, i.e. if all to receive the second newsletter on the same day, then this should be ONE call to SendGrid. INTERFACE: On top of all this, we need a very simple form-based interface for inputting and editing the email templates that go into each thread, as well as the timing of the email sequences. We do have multiple different threads, so the interface needs to take that into account. The interface does not need to be pretty, it just needs to work! THANKS FOR YOUR BIDS! Thanks for reading this project. Hope to hear from you guys soon.