For my website I'd like to setup an automatic emailer for users. The database for the website is managed through php and mySQL. I'd like the emailer program to check the user's maintenance schedule (part of the website features) in the database on a regular basis and send out simple text email reminders.

Would a cron job be the best for accomplishing this goal? What questions and specifications should I look into? I'd like to post this project to freelancer.com but I want to know more so the project details are correct. How many hours would it take to finish this type of project/approximate cost?

Thanks for any help and all advice is appreciated.

yes, I would handle this as a cron job. you really don't need much more than that... well you need the code to execute checking the user's schedule and sending the email (which is the bigger part of this project), the cron setup is a smaller part

If all the variables are defined then I'd allocate an hour for writing and an hour for testing.

By variables I mean that you should document all the possible circumstances in which an email should be sent, the recipient(s) for each email, the content of each email (subject and body).

That said, are the tasks likely to change much - do you need a degree of future-proofing built in?