Several Smtp/ email questions

[kutchbhi]

I have a php/html website.
There's a php based 'feedback form' on my site , which uses the 'mail()' function of php to send emails. Both "to:" and "from:" addresses are set based on user input and then the mail is sent.

I am having a few problems and questions

#. any emails sent to a hotmail or yahoo address end up being in the junk folder. any way of preventing this ?

#exactly how does php sends the emails when using the mail() function? using the smtp server ?

#how many messages can be sent per hour for free on free hosting ?

Thanks

 

[nbwebmaster]

#2. PHP uses a program called sendmail to send email, however it can be configured to use an SMTP server, though I am pretty sure x10hosting uses sendmail.