Rmail Files and Inboxes
The operating system places incoming mail for you in a file that we
call your inbox. When you start up Rmail, it runs a C program
called movemail to copy the new messages from your inbox into
your primary Rmail file, which also contains other messages saved from
previous Rmail sessions. It is in this file that you actually read the
mail with Rmail. This operation is called getting new mail. You
can get new mail at any time in Rmail by typing g.
The variable rmail-primary-inbox-list contains a list of the
files which are inboxes for your primary Rmail file. If you don't set
this variable explicitly, it is initialized from the MAIL
environment variable, or, as a last resort, set to nil, which
means to use the default inbox. The default inbox is
/var/mail/username, /usr/spool/mail/username,
or /usr/mail/username, depending on your operating system.
To see what the default is on your system, use C-h v
rmail-primary-inbox <RET>. You can specify the inbox file(s) for
any Rmail file with the command set-rmail-inbox-list; see
Rmail Files.
There are two reasons for having separate Rmail files and inboxes.
- The inbox file format varies between operating systems and according to
the other mail software in use. Only one part of Rmail needs to know
about the alternatives, and it need only understand how to convert all
of them to Rmail's own format.
- It is very cumbersome to access an inbox file without danger of losing
mail, because it is necessary to interlock with mail delivery.
Moreover, different operating systems use different interlocking
techniques. The strategy of moving mail out of the inbox once and for
all into a separate Rmail file avoids the need for interlocking in all
the rest of Rmail, since only Rmail operates on the Rmail file.
Rmail was written to use Babyl format as its internal format. Since
then, we have recognized that the usual inbox format on Unix and GNU
systems is adequate for the job, and we plan to change Rmail to use that
as its internal format. However, the Rmail file will still be separate
from the inbox file, even on systems where their format is the same.
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