Configuring Mail server for sending mails

view story

http://stackoverflow.com – I have an Ec2 instance on amazon AWS. i have installed , dovecot,postfix on server, mail incoming mail server is IMAP mail.xxxx.com . I am able to configure my mails with gmail, outlook etc, using the IMAP. and can send and receive emails, The problem is that i want to send emails through PHP code using my mail server. means mails sent from may sever email address. I have used PHPmailer earlier to send emails using gmail mail server SMTP settings. But now i do not know about the SMTP settings for my server, should i need to install and configure sendmail and then SMTP and then sending emai (HowTos)