~~socialite:icon reddit googleplus stumbleupon twitter~~
  
===== Electronic Mail Overview =====
There are three components to electronic mail:
    * MAIL USER AGENT - e.g. mailx, elm. dtmail, pine
    * MAIL TRANSFER AGENT - e.g. sendmail
    * MAIL DELIVERY AGENT - e.g. SMTP, local mailer, UUCP
MAILBOX - a file on a mail server to store mail, typically in /var/mail

{{general:mail.gif}}

MAIL HOST - main mail computer, mail is sent here when the other mail computer
can't deliver it
MAIL SERVER - maintains mailboxes
CLIENT - receives mail, usuall no local /var/mail
The mail directory (e.g. /var/mail), can be NFS mounted if the mail server
isn't the users local box. This saves having numerous mail servers.
==== Typical_Local_Mail_Setup ====
<code>
   /bin/mailx user sends mail 
          | 
          | 
          V 
  sendmail messages routed 
          | 
          | 
          V 
  local mailer delivers to mailbox 
          | 
          | 
          V 
  mailx message read
</code>
Sendmail parses the message and using the rules in **sendmail.cf**, works out where
to send it. It acts as an interface between mail user agent and mail transport
agent, e.g. SMTP . It also supports forwarding mechanisms e.g. aliases,
.forward file.
==== Remote_Mailing ====
Mail is sent via the mail gateway. For mail sent over the internet, sendmail
typically starts a SMTP session with the remote sendmail daemon. Usually,
rather then deliver to the actual destination (which could be a PC over a modem
line, probably not active), it delivers to the mail exchange server. 

During the
transfer a DNS lookup is triggered. This finds the mail exchange for the domain
from the MX record (trying the one with the highest priority first). From
there, the user can recover the mail using POP3 (which periodically and/or on
demand, downloads the mail) or IMAP which lists the mail on the mail exchange.

  
<alert type="warning" icon="fa fa-question-circle-o"> **Still stuck? Maybe we can help.** Contact us [[https://www.upwork.com/o/profiles/users/_~01207a4bc438b48c6e|at Upwork]]</alert>
<alert type="info" icon="fa fa-exclamation-circle"> Never miss a thing [[http://www.justsomestuff.co.uk/subscribe.php|subscribe to our newsletter]] {{glyphicon>envelope}}
or follow us [[http://twitter.com/itsjustsomestuf|on twitter]] {{glyphicon>hand-left}}</alert>                        
<alert type="info" icon="fa fa-check">  For more super cool techie stuff [[http://www.justsomestuff.co.uk/theblog|check out our blog!!]]</alert>
                                                                                
===Recent Changes===                                                            
                                                                                
{{changes>}}                                                                    
                                                                                
<callout type="info" icon="fa fa-user-plus">                                    
====Contribute to this wiki====                                                 
Why not help others by sharing your knowledge? Contribute something to this wiki and
[[http://www.justsomestuff.co.uk/hall_of_fame.html|join out hall of fame!]]\\   
[[http://www.justsomestuff.co.uk/theblog/contact-page|Contact us]] for a user name and password                          
</callout>