Mail Administration Guide
    
U
 
 -U flag (mailer description) ( Index Term Link )
 
 -u flag (mailer description) ( Index Term Link )
 
 $u macro (sendmail program) ( Index Term Link ) ( Index Term Link ) ( Index Term Link ) ( Index Term Link ) ( Index Term Link )
 
 undelivered messages
  See also troubleshooting
  error-caused ( Index Term Link )
  storage of ( Index Term Link ) ( Index Term Link )
  timeout for ( Index Term Link ) ( Index Term Link ) ( Index Term Link )
  troubleshooting ( Index Term Link ) ( Index Term Link ) ( Index Term Link )
 
 underscore (_), in mailbox names ( Index Term Link )
 
 UNIX argument vector/exit status interface, sendmail program ( Index Term Link )
 
 UNIX over pipes interface, sendmail program ( Index Term Link )
 
 UNIX-style From lines ( Index Term Link ) ( Index Term Link ) ( Index Term Link ) ( Index Term Link )
 
 UNIX-to-UNIX Copy
  See uucp mailer; UUCP (UNIX-to-UNIX Copy Protocol)
 
 uppercase preservation
  host names ( Index Term Link )
  user names ( Index Term Link )
 
 user agents
  See mail user agents
 
 user ID for mailers
  resetting not done ( Index Term Link )
  setting default ( Index Term Link )
 
 user names
  mailbox names and ( Index Term Link )
  uppercase preserved ( Index Term Link )
 
 users
  alias creation by ( Index Term Link )
  custom mailer specification by ( Index Term Link )
  full name argument (sendmail program) ( Index Term Link )
 
 /usr/bin/aliasadmin command
  See aliasadmin command
 
 /usr/bin directory, mail services contents ( Index Term Link )
 
 /usr/bin/mail command ( Index Term Link ) ( Index Term Link ) ( Index Term Link )
 
 /usr/bin/mailcompat filter ( Index Term Link )
 
 /usr/bin/mailq command ( Index Term Link ) ( Index Term Link ) ( Index Term Link ) ( Index Term Link )
 
 /usr/bin/mailstats program ( Index Term Link ) ( Index Term Link )
 
 /usr/bin/mailx command
  See mailx command
 
 /usr/bin/mconnect program ( Index Term Link ) ( Index Term Link )
 
 /usr/bin/newaliases program ( Index Term Link ) ( Index Term Link ) ( Index Term Link )
 
 /usr/bin/rmail program ( Index Term Link )
 
 /usr/bin/vacation command ( Index Term Link ) ( Index Term Link ) ( Index Term Link )
 
 /usr/lib directory, mail services contents ( Index Term Link )
 
 /usr/lib/mail.local mailer ( Index Term Link ) ( Index Term Link )
 
 /usr/lib/sendmail program
  See sendmail program
 
 /usr/sbin/in.comsat daemon ( Index Term Link )
 
 /usr/sbin/syslogd error message logger ( Index Term Link ) ( Index Term Link ) ( Index Term Link )
 
 UUCP (UNIX-to-UNIX Copy Protocol)
  mailer description semantics and ( Index Term Link )
  mailers using ( Index Term Link )
  route-based addressing and ( Index Term Link )
  route-independent addressing and ( Index Term Link )
  sendmail program and ( Index Term Link )
 
 uucp mailer
  described ( Index Term Link )
  mail gateway configuration and ( Index Term Link )
  sendmail program and ( Index Term Link )
  specifying in sendmail.cf ( Index Term Link )
  testing mail configuration with ( Index Term Link )
 
 uux mailer ( Index Term Link )