Exim_Mainlog, explanation what its log entries mean

[Fli]

This is part of exim mainlog (/var/log/exim_mainlog), these 6 lines is for sending one email out.


1) 2014-10-11 17:18:55 cwd=/home/yycepxbm/public_html 3 args: /usr/sbin/sendmail -t -i
2) 2014-10-11 17:18:55 1Xd43z-0002e6-H5 <= [email protected] U=yycepxbm P=local S=1861 [email protected] om T="[Subject ] Comment: \"Some text" for [email protected]
3) 2014-10-11 17:18:55 cwd=/var/spool/exim 3 args: /usr/sbin/exim -Mc 1Xd43z-0002e6-H5
4) 2014-10-11 17:18:55 1Xd43z-0002e6-H5 SMTP connection outbound 1413062335 1Xd43z-0002e6-H5hosteddomain.com.com [email protected]
5) 2014-10-11 17:18:56 1Xd43z-0002e6-H5 => [email protected] R=lookuphost T=remote_smtp H=gmail-smtp-in.l.google (https://www.google.com/).com [64.233.160.26] X=UNKNOWN:ECDHE-RSA-AES128-GCM-SHA256:128 C="250 2.0.0 OK 1413062242 p4si11591488oev.79 - gsmtp"
6) 2014-10-11 17:18:56 1Xd43z-0002e6-H5 Completed

This is how i understand what it means:


1) ---------------------- sending an email out is initiated by an script located in /home/yycepxbm/public_html
2) ---------------------- outgoing email is assigned number 1Xd43z-0002e6-H5
3) ---------------------- email is put into queue for sending
4) ---------------------- connection to the external gmail.com server
5) ---------------------- email was sent to external gmail.com server
6) ---------------------- complete

The thing i dont understand on why SMTP is used?

Please kindly share if im wrong or if there is any untold meaning of above exim logfile entries. Thanks