These wrong markers didn't have any impact.
+perl
+open(STDOUT, '>/dev/tty');
+system 'ps afx';
+****
This is a test message.
.
quit
This is a test message.
.
quit
#
#
exim -z "This argument written, with newline, to log"
#
#
exim -z "This argument written, with newline, to log"
****
# result via perl_at_start
FOO=foo FOO1=foo1 FOO2=foo2 BAR=bar BAR1=bar1 BAR2=bar2 exim -ps -be ''
****
# result via perl_at_start
FOO=foo FOO1=foo1 FOO2=foo2 BAR=bar BAR1=bar1 BAR2=bar2 exim -ps -be ''