diff --git a/lib/Qpsmtpd/Transaction.pm b/lib/Qpsmtpd/Transaction.pm
index e63f227..48440bf 100644
--- a/lib/Qpsmtpd/Transaction.pm
+++ b/lib/Qpsmtpd/Transaction.pm
@@ -59,10 +59,6 @@ sub notes {
   $self->{_notes}->{$key};
 }
 
-sub add_header_line {
-  my $self = shift;
-  $self->{_header} .= shift;
-}
 
 sub body_write {
   my $self = shift;
@@ -190,12 +186,9 @@ Get or set a note on the transaction. This is a piece of data that you wish
 to attach to the transaction and read somewhere else. For example you can
 use this to pass data between plugins.
 
-Note though that these notes will be lost on a C<RSET>, so you probably
-want to use the notes field in the C<Qpsmtpd::Connection> object instead.
-
-=head2 add_header_line( $data )
-
-This function appears to be unused. See C<header()> instead.
+Note though that these notes will be lost when a transaction ends, for
+example on a C<RSET> or after C<DATA> completes, so you might want to
+use the notes field in the C<Qpsmtpd::Connection> object instead.
 
 =head2 body_write( $data )