Action mailer noob

Hi guys, a noob in rails here

I did some searching on the net about how to send email to diffrent
domain adresses like google, yahoo and stuff…and the guides that i
found were a bit more confusing.

for example at this adress
the last two examples Action Mailer Configuration, Action Mailer
Configuration for GMail

The thing is that they are so diffrent…and if i wanna send mails to
yahoo, or hotmail or whatever, what should i do?

but before al this, if i wanna send a small mail on my mac, just to
see how this action mailer stuff works, is there something i should
change in my app?

a million thx in advance,