 Linux- MUA ,     
  sendmail.   ,       -
   Internet, sendmail     -
 Internet-.  sendmail      SMTP
(Simple Mail Transfer Protocol      ),
sendmail    SMTP.

   Red Hat  sendmail    
MDA  procmail.   procmail     
   .   procmail   
           -
,  .        -
         ,  
        
.  UNIX- MUA     -
  ,       MDA, -
 procmail.  MUA   .

        sendmail. -
 MUA        POP 
1.       sendmail. , 
       -
 sendmail (  ).     
SMTP.   SMTP-   , ,   -
 Internet-,       .



    ,     Internet,  
  ,      
    .      -
       ,    -
 .

    Internet     . -
      IP-   ,   -
    .    
     ,       
Internet-,            -
 POP  IMAP.      ,    
,      sendmail   SMTP-  .

  sendmail     ,   -
   SMTP-.    , -
        
Internet   ,      . 
       
Internet-    25,     -
     .   
 ISP.

630  V.     