Complete Sendmail Confusion!

Hey, All,

I'm just delving into the topic of server-side programming, and I'm trying to use Sendmail to... well... send mail :).

I am sooooo confused! I really don't know where to start....
I've used mail() with PHP (without doing any sendmail configuration) and I a message was successfully sent (from www@imac.localhost, appearantly my default or something....). But I don't know anything about the process.

I've read the sendmail man file, but I'm still confounded beyond belief. Can someone help me understand how to configure sendmail for my needs?

I currently am self hosting, from an apache server on my mac. I've got nothing but an IP address. My computer (thus, my server) is not always on. How can I set up an account such as "stalepretzel@174.31.53.142"? Can I configure sendmail to use my gmail account?

Yes, I'm a sendmail noob ;). I'd GREATLY appreciate any help.

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