4.3BSD - /usr/man/cat7/mailaddr.0

MAILADDR(7)                                                        MAILADDR(7)


NAME
       mailaddr - mail addressing description

DESCRIPTION
       Mail  addresses  are based on the ARPANET protocol listed at the end of
       this manual page.  These addresses are in the general format

                 user@domain

       where a domain is a hierarchical dot separated list of subdomains.  For
       example, the address

                 eric@monet.Berkeley.ARPA

       is  normally  interpreted  from right to left: the message should go to
       the ARPA name tables (which do not correspond exactly to  the  physical
       ARPANET), then to the Berkeley gateway, after which it should go to the
       local host monet.  When the message reaches monet it  is  delivered  to
       the user ‘‘eric’’.

       Unlike some other forms of addressing, this does not imply any routing.
       Thus, although this address is specified as an ARPA address,  it  might
       travel by an alternate route if that were more convenient or efficient.
       For example, at Berkeley  the  associated  message  would  probably  go
       directly  to monet over the Ethernet rather than going via the Berkeley
       ARPANET gateway.

   Abbreviation.
       Under certain circumstances it may not be necessary to type the  entire
       domain  name.  In general anything following the first dot may be omit‐
       ted if it is the same as the domain from which you are sending the mes‐
       sage.   For  example,  a user on ‘‘calder.Berkeley.ARPA’’ could send to
       ‘‘eric@monet’’ without adding the ‘‘.Berkeley.ARPA’’ since  it  is  the
       same on both sending and receiving hosts.

       Certain  other  abbreviations  may  be permitted as special cases.  For
       example, at Berkeley ARPANET hosts can be referenced without adding the
       ‘‘.ARPA’’  as  long  as  their  names do not conflict with a local host
       name.

   Compatibility.
       Certain old address formats are converted to the new format to  provide
       compatibility with the previous mail system.  In particular,

                 host:user

       is converted to

                 user@host

       to be consistent with the rcp(1C) command.

       Also, the syntax:

                 host!user

       is converted to:

                 user@host.UUCP

       This  is normally converted back to the ‘‘host!user’’ form before being
       sent on for compatibility with older UUCP hosts.

       The current implementation is not able to route messages  automatically
       through the UUCP network.  Until that time you must explicitly tell the
       mail system which hosts to send your message through  to  get  to  your
       final destination.

   Case Distinctions.
       Domain  names (i.e., anything after the ‘‘@’’ sign) may be given in any
       mixture of upper and lower case with the exception of  UUCP  hostnames.
       Most  hosts  accept  any  combination  of  case in user names, with the
       notable exception of MULTICS sites.

   Differences with ARPA Protocols.
       Although the UNIX addressing scheme is based on the ARPA mail  address‐
       ing protocols, there are some significant differences.

       At  the  time of this writing DARPA is converting to real domains.  The
       following rules may be useful:

       ·   The   syntax   ‘‘user@host.ARPA’’   is   being   split   up    into
       ‘‘user@host.COM’’, ‘‘user@host.GOV’’, and ‘‘user@host.EDU’’ for commer‐
       cial, government, and educational institutions respectively.

       · The syntax ‘‘user@host’’ (with no dots) has traditionally referred to
       the  ARPANET.   In  the  future  this  semantic will not be continued —
       instead, the host will be assumed to  be  in  your  organization.   You
       should start using one of the syntaxes above.

       ·  Host  names of the form ‘‘ORG-NAME’’ (e.g., MIT-MC or CMU-CS-A) will
       be changing to ‘‘NAME.ORG.XXX’’ (where ‘XXX’ is COM, GOV, or EDU).  For
       example, MIT-MC will change to MC.MIT.EDU.  In some cases names will be
       split apart even if they do not have  dashes.   For  example,  USC-ISIF
       will probably change to F.ISI.USC.EDU.

   Route-addrs.
       Under some circumstances it may be necessary to route a message through
       several hosts to get it to the final destination.  Normally this  rout‐
       ing  is  done automatically, but sometimes it is desirable to route the
       message  manually.   Addresses  which  show  these  relays  are  termed
       ‘‘route-addrs.’’  These use the syntax:

                 <@hosta,@hostb:user@hostc>

       This  specifies that the message should be sent to hosta, from there to
       hostb, and finally to hostc.  This path is forced even if  there  is  a
       more efficient path to hostc.

       Route-addrs  occur frequently on return addresses, since these are gen‐
       erally augmented by the software at each host.  It is generally  possi‐
       ble  to  ignore all but the ‘‘user@host’’ part of the address to deter‐
       mine the actual sender.

   Postmaster.
       Every site is required to have a user or user alias designated  ‘‘post‐
       master’’ to which problems with the mail system may be addressed.

   Other Networks.
       Some other networks can be reached by giving the name of the network as
       the last component of the domain.  This is not a standard  feature  and
       may  not  be supported at all sites.  For example, messages to CSNET or
       BITNET  sites   can   often   be   sent   to   ‘‘user@host.CSNET’’   or
       ‘‘user@host.BITNET’’ respectively.

BERKELEY
       The following comments apply only to the Berkeley environment.

   What’’s My Address?
       If you are on a local machine, say monet, your address is

                 yourname@monet.Berkeley.ARPA

       However,  since  most  of  the  world does not have the new software in
       place yet, you will have  to  give  correspondents  slightly  different
       addresses.  From the ARPANET, your address would be:

                 yourname%monet@Berkeley.ARPA

       From UUCP, your address would be:

                 ucbvax!yourname%monet


   Computer Center.
       The  Berkeley  Computer Center is in a subdomain of Berkeley.  Messages
       to the computer center should be addressed to:

                 user%host.CC@Berkeley.ARPA

       The alternate syntax:

                 user@host.CC

       may be used if the message is sent from inside Berkeley.

       For the time being Computer Center hosts are known within the  Berkeley
       domain, i.e., the ‘‘.CC’’ is optional.  However, it is likely that this
       situation will change with time as both the Computer Science department
       and the Computer Center grow.

BUGS
       The RFC822 group syntax (‘‘group:user1,user2,user3;’’) is not supported
       except in the special case of ‘‘group:;’’ because of  a  conflict  with
       old berknet-style addresses.

       Route-Address syntax is grotty.

       UUCP- and ARPANET-style addresses do not coexist politely.

SEE ALSO
       mail(1),  sendmail(8);  Crocker, D. H., Standard for the Format of Arpa
       Internet Text Messages, RFC822.


4.2 Berkeley Distribution         May 6, 1986                      MAILADDR(7)