You are right, but one thing is really strange - the same set of regex rules (currently 13 of them) works great on about 10 machines and doesn't work on those two (only).
The input line with sendmail contains

<sys_date> sendmail[pid]: <i>some stuf</i> relay=some.host.net [ip_add
+r], <i>some stuf</i> Relaying denied
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Well - even if this rule or the input is wrong, then ok - it can be wrong - never mind - I'll fix it - but then, why it works on other computers?
I'm afraid of what I've mentioned - even very simple regex works only case-sensitive. For example this code I've written about a year ago:

#!/usr/bin/perl
use strict;

my @in;
open (FH, "ps ax |");
chomp(@in = <FH>);
close (FH);
$_ = join(//,@in);
chomp;
if (! /\/Rlogger.pl/i) { system("/etc/rc.d/rc.remote-logger") };
if (! /\/mle/i) { system("/etc/rc.d/rc.mle") };
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I know it's dirty and not professional - sorry for that :-) Anyway mle is recognized as it should be but Rlogger.pl is not - it's done case-sensitive (on those 2 machines only).
I can always do some work-around to solve this problem in the other way, but I got supprised by those non-working regex lines. I can't find anything strange in system configuration, I've compiled perl from pure tarball several times on those machines and nothing helped so far :-(

Tnx for suggestions
Greetz, Tom.