how to change daily run output's subject line?

[Matthias F. Brandstetter]

Hi all,

as like every other FreeBSD machine, my FreeBSD based server sends me an 
daily (security) output every night. I know where to change some settings 
like where the email should go to etc. But is there any chance to change 
subject line of this auto generated email?

Greetings and TIA, Matthias

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     Treehouse of Horror