Send mail setting

Email Process,

• MSP(Mail Submission Program)
• MTA(Mail Transport Agent)
• MDA(Mail Delivery Agent)

Configuration file,

• /etc/mail/sendmail.cf - the main configuration file for sendmail
• /etc/mail/sendmail.mc - sendmail macro configuration file
  
• /etc/mail/submit.cf - configure sendmail operation when connected by MSP(email client software)
• /etc/aliases - configure local user aliases and need use newaliases command to hash to aliases.db before using.
  
• /etc/mail/local-host-names - lists the aliases and domain, which the mail server will accept in an incoming e-mail address for local delivery
• /etc/mail/access - after modification need run "make" in /etc/mail folder
  
• /var/named/chroot/var/named/db.domain DNS setting file
• Log file: /var/log/maillog

Configuration

• set in sendmail.cf

• Get host ip address,
  
• Set DNS server IP in /etc/resolv.conf and make sure search follow with correct domain name
• example db.domain file
  domain.com. IN NS example.domain.com.
  example.domain.com. IN A 192.168.1.12
  domain.com. IN MX 10 example
• Allow other PC sent email though the smtp server(by default sendmail only allow user send email on the server) by set line DaemonPort0ptions=Port=smtp,Addr=127.0.0.1, Name=MTA to notes in the sendmail.cf file
• netstat -tupln | grep :25 - display on the port 25 which program listen on which address t - tcp, u - udp, P - program name, L - listening port, n
  
• service sendmail restart - active the above setting
  
• set in sendmail.mc
  
  • Back up sendmail.mc and sendmail.cf
    
  • put dnl in front of DAEMON_OPTIONS('Port=smtp,Addr=127.0.0.1, Name=MTA')
    
  • m4 /etc/mail/sendmail.mc > /etc/mail/sendmail.cf
  • diff /etc/mail/sendmail.cf /etc/mai/sendmail.cf.bak - compare the new and old sendmail.cf file