im talking about setting in admin > configuration > email option .
where you have smtp setting . such as account , port , host . etc.
smtp's job is to relay emails .. logically , i guess , php mail function needs that to send email , otherwise , how would email will be send from your shop ? not through your email client on your computer but through server. ..
once that is been set . you can setup both pop3, and smtp on email client program to send and receive emails



