+\fBMYMAIL_DB_FILE\fR
+defaut value for the --db-file-output argument
+
+.SH "SEARCH CONDITIONS"
+
+A search condition is either a time-related condition
+('today', 'yesterday', etc.), or a single-character key, followed by a
+space and a regexp, which can itself contain spaces.
+
+If it is prefaced by the character "!", a condition is negated and has
+to be false for a mail to be selected.
+
+.TP
+\fBf <regexp>\fR (from)
+selects mails whose leading line 'From', or fields From:, Sender:,
+Reply-To:, or Return-Path: matches the regexp.
+.TP
+\fBt <regexp>\fR (to)
+selects mails whose field To:, Cc:, or Bcc: matches the regexp.
+.TP
+\fBp <regexp>\fR (participant)
+selects mails that would be selected by \fBf\fR or \fBt\fR.
+.TP
+\fBs <regexp>\fR (subject)
+selects mails whose field Subject: matches the regexp.
+.TP
+\fBd <regexp>\fR (date)
+selects mails whose field Date: matches the regexp.
+.TP
+\fBb <regexp>\fR (body)
+selects mails whose body matches the regexp. Evaluating such a
+condition requires to read the original mboxes completely, which can
+be slow. However, header conditions are checked first to read the
+bodies only for mails which fulfill them entirely.
+.TP
+\fB8h\fR, \fB24h\fR, \fB48h\fR, \fBweek\fR, \fBmonth\fR, \fBtrimester\fR,
+and \fByear\fR selects mails received during the last 8, 24, 24, 48, 7
+* 24 hours, 31 * 24 hours, 92 * 24 hours, and 365 * 24 hours respectively.
+.TP
+\fBtoday\fR
+selects mails received since midnight.
+.TP
+\fByesterday\fR
+selects mails received yesterday.
+.TP
+\fBmonday\fR, \fBtuesday\fR, ..., \fBsunday\fR
+selects mails received the most recent such day of the week.