.RS 4
.TP 4
-.B \-\-format=(json|text)
+.B \-\-format=(text|json|mbox)
.RS 4
.TP 4
.B text
-The default plain-text format has text-content MIME parts
+The default plain-text format has all text-content MIME parts
decoded. Various components in the output,
.RB ( message ", " header ", " body ", " attachment ", and MIME " part ),
will be delimited by easily-parsed markers. Each marker consists of a
.TP 4
.B json
-Format output as Javascript Object Notation (JSON). JSON output always
-includes all messages in a matching thread; in effect
+The output is formatted with Javascript Object Notation (JSON). This
+format is more robust than the text format for automated
+processing. JSON output always includes all messages in a matching
+thread; in effect
.B \-\-format=json
implies
.B \-\-entire\-thread
+.RE
+.RS 4
+.TP 4
+.B mbox
+
+All matching messages are output in the traditional, Unix mbox format
+with each message being prefixed by a line beginning with "From " and
+a blank line separating each message. Lines in the message content
+beginning with "From " (preceded by zero or more '>' characters) have
+an additional '>' character added. This reversible escaping
+is termed "mboxrd" format and described in detail here:
+http://homepage.ntlworld.com/jonathan.deboynepollard/FGA/mail-mbox-formats.html
+
.RE
A common use of
.B notmuch show