even though such messages violate the SMTP protocol.
.SH "CONTROL FILES"
.TP 5
+.I addrcheck.cdb
+A database of acceptable mailboxes. If present, this is used to report
+erroneous RCPT TO commands, which can reduce the amount of junk mail
+accepted. It contains an encoding of the virtual domains map
+.RB ( \c
+.BI V domain
+maps to
+.IR prefix ),
+the local domains
+.RB ( \c
+.BI @ domain
+maps to an empty string), and the available local parts
+.RB ( \c
+.BI L mailbox
+maps to
+.B +
+if the address is valid or
+.B \-
+if not). It's best made using
+.BR qmail-valid-addresses (8).
+.TP 5
+.I addrcheck-delay
+Delay in seconds before reporting bad mailbox names after the
+.I addrcheck-slow
+limit is reached. The default is 2.
+.TP 5
+.I addrcheck-limit
+Number of bad mailbox names to tolerate before dropping the connection.
+Zero means an infinite number. The default is 50.
+.TP 5
+.I addrcheck-slow
+Number of bad mailbox names to tolerate before imposing delays. The
+default is 5.
+.TP 5
.I badmailfrom
Unacceptable envelope sender addresses.
.B qmail-smtpd