I am a relatively new web developer looking for a hobby project thats substantial enough to actually learn a fair bit of php and other web related stuff.
I'm thinking of a small simple webmail client but am unsure exactly where to start.
I'm sure I will be using the php imap support a fair amount but but does anyone have any specific pointers on where to start off?
Also, I'm going to try and incorporate as much HTML5 functionality as possible; again is there any advice on this?
OK if you are new, why you want make so hard think ... ??? :D for emails try this ... http://phpmailer.worxware.com/
David, you say you come from a programming background. What programming have you done? What languages do you know?
Another thought: You say you want to "learn a fair bit of php and other web related stuff". I'm not sure what you mean by "web related stuff", but I guess that includes HTML. Why not simply start a web page about something you're interested in? That will give you plenty of opportunity to use PHP, HTML, CSS, Flash, javascript etc. But perhaps you're looking for a narrower project?
If I were you, I'd download something like Roundcube or SquirrelMail and look at how they do things. If you study the code of an existing, stable project you'll learn a lot about best practices. Roundcube uses a fair amount of JavaScript, while SquirrelMail does not. Roundcube also uses jQuery, which would be good to familiarize yourself with if you plan on doing much with JavaScript. As far as HTML5 goes, check out this site, and start working in any features you feel like playing with (a lot of it is still largely unsupported):
Roundcube: http://roundcube.net/
SquirrelMail: http://squirrelmail.org/