CentOS 5 :: How To Configure Mutt For SMTP (Gmail) Account

# uname -a
Linux newserver 2.6.18-194.26.1.el5 #1 SMP Tue Nov 9 12:54:40 EST 2010 i686 i686 i386 GNU/Linux

The configuration file for mutt (.muttrc ) :
root@newserver ~]# cat .muttrc
set from = "kostas123@gmail.com"
set realname = "Kostas xxxxx"
set imap_user = "kostas123@gmail.com"
set imap_pass = "xxxxxxxxxx"
set folder = "imaps://imap.gmail.com:993"
set spoolfile = "+INBOX"
set postponed ="+[Gmail]/Drafts"
set header_cache =~/.mutt/cache/headers
set message_cachedir =~/.mutt/cache/bodies
set certificate_file =~/.mutt/certificates
set smtp_url = "smtp://kostas123@smtp.gmail.com:587/"
set smtp_pass = "xxxxxxxxxx"
set move = no
set imap_keepalive = 900

root@newserver ~]# service sendmail status
sendmail (pid 6428) is running...
root@newserver ~]# mutt
Error in /root/.muttrc, line 8: header_cache: unknown variable
Error in /root/.muttrc, line 9: message_cachedir: unknown variable
Error in /root/.muttrc, line 11: smtp_url: unknown variable
Error in /root/.muttrc, line 12: smtp_pass: unknown variable
source: errors in /root/.muttrc
Press any key to continue...

Mutt can only read email's from my gmail account, but no emails can be send through gmail to the Internet. I need some guide for Mutt , don't know how to configure it , for sending emails via my gmail account. I tried many muttrc conf files from the Internet and even tried to configure my own muttrc file , but still no luck. My windows xp box ( Outlook Express ) is configured and works with gmail account , but I would like to explore the power of Linux.