[SYMBOL] [A] [B] [C] [D] [E] [F] [G] [H] [I] [J] [K] [L] [M] [N] [O] [P] [Q] [R] [S] [T] [U] [V] [W] [X] [Z] u delivery agent flag  U delivery agent flag  U= delivery agent equate  2nd  3rd  UDB_DEFAULT_SPEC compile-time macro  uid (user-id)     assume specified      running agent as  UIUC IDA sendmail  unavailable resource error message  Unbalanced warning  undeliverable addresses in aliases  uniformity  Unix mailbox file  UnixFromLine option  unknown configuration line warning message  unknown local users  unknown mailer error message  unqualified names  2nd  upgrading sendmail  uppercase  [See case sensitivity] use_ct_file feature  use_cw_file feature  USE_DOUBLE_FORK compile-time macro  USE_ENVIRON compile-time macro  USE_VENDOR_CF_PATH compile-time macro  usenet delivery agent  User Database      rewriting addresses and  2nd  User Database key  user database type  user names     case sensitivity and      of recipients  User unknown error message  user-id (uid)     assume specified      running agent as  UserDatabaseSpec option  USERDB compile-time macro  users  [See also recipients]     $: operator and  2nd  3rd      ~/.forward file of  2nd  3rd      alias delivery to      as LHS of alias      default identities for      groups      local         delivery to  2nd  3rd          unknown      mailing list instructions for      marked with +      running sendmail manually and      trusted  2nd  3rd  4th      unavailable      verifying with SMTP  USESETEUID compile-time macro  USING_NETSCAPE_LDAP compile-time macro  UUCP  2nd      $k macro and  2nd      eliminating support for      F=d delivery agent flag and      local handling of      macros for repays and      preferred delivery agent for  uucp delivery agent  UUCP_RELAY mc macro  uucpdomain feature  UUCPSMTP mc macro  uuencode/uudecode utilities