Change email routine to use phpmailer() lib

Need to change an admin? page to send emails using phpmailer lib instead of mail() PHP function, add the capability to attach files and make users reply to these emails in a way that the administrators have the control over all these messages. It should be something similar to a forum where people posts replies over answers. ## Deliverables Currently, if an user enters in the website to request a pre-order of a car part, he is directed to a form where he fill-out his personal data and information about the part he is looking for (such as name, code and some car's data). The information about the user and its car parts are added to the database (separate tables) and the reponsibles to the Parts Department receives an email requesting him/her to access the administration page and answer its client's request in a form. The output is sent to the client to its e-mail address and the client answer its email to the departments operator, directly to its e-mail address. The emails are been sent using PHP's mail() function using the mailserver onto the webserver. Now I need to improve this process a bit as follows: - Once the client has registered at the first time or when he submits the first form (with his data included already), then a cookie (or something else similar) will be placed and when the user access other forms, he doesn't need to place its personal data again. The scripts should be clever enough to hold its user's data and add them within the database once a new form is filled out, but the user doesn't need to type it again. PS: the forms are already working, just this extra capability is needed. - Currently in the administration page, our assistants respond our client's contacts sending emails from our administration page and the client reply to its email straight to the assistant's email address. Now, we need to keep track of all conversations. Then we came up with the idea of keep responding to our client's requests using the current method but when the client replies to our message, he must click in a link sent on his email where a page will open (this is the new feature) and he would reply to his message on that form, so this will be stored to the database and then we will keep track of it. Keep in mind that currently we have a page showing the client's first contact and our first response to him, and with this new capability, all the conversation must be shown in this already working page. - Add the capability to attach one file when sending e-mails to the clients from the form above. - Change the way the emails are being sent from using the mail() function to use the class phpmailer() because the emails need to be sent from a different mail server.