Index: openacs-4/packages/acs-mail-lite/tcl/utils-procs.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/acs-mail-lite/tcl/utils-procs.tcl,v
diff -u -r1.9 -r1.9.2.1
--- openacs-4/packages/acs-mail-lite/tcl/utils-procs.tcl	15 Aug 2018 16:24:28 -0000	1.9
+++ openacs-4/packages/acs-mail-lite/tcl/utils-procs.tcl	1 Feb 2021 10:55:56 -0000	1.9.2.1
@@ -42,7 +42,7 @@
     #
     set subject [string trim $subject]
 
-    if {[regsub -all {[\r\n]} $subject " " s]} {
+    if {[regsub -all -- {[\r\n]} $subject " " s]} {
         ad_log warning "subject line contains line breaks (replaced by space): '$subject' -> '$s'"
         set subject $s
     }