You might want to stick a die and a message on

my $log = `tail -$lines /var/log/syslog|egrep -i '$day'|egrep -i 'defe
+rred'`;
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such as

my $log = `tail -$lines /var/log/syslog|egrep -i '$day'|egrep -i 'defe
+rred'` or die ("No Deferred messages\n");
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or place a check for nothing found. There is a chance no deferred mail gets logged and with the current code you get these messages when the job runs.

Use of uninitialized value in pattern match (m//) at dm line 45.
Use of uninitialized value in pattern match (m//) at dm line 51.
Use of uninitialized value in subtraction (-) at dm line 58.
Use of uninitialized value in subtraction (-) at dm line 58.
deferred messages ocurred withing 1 minute of each other
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