Disclaimer: This post has been copied completely from this other post. I have here my own version because I don't want to keep track of the link and I think you guys can find it useful, too. All the credit must go to the original author of the post.

By default, logwatch sends you an email with a daily report. This is kind of annoying because, let's be clear, you don't read eeevery day the report. To configure logwatch to send you the reports weekly you can execute this commands:

$ sudo -i  
$ echo "Range = between -7 days and -1 days" >>
/etc/logwatch/conf/logwatch.conf  
$ echo "Output = html" >> /etc/logwatch/conf/logwatch.conf  
$ mv /etc/cron.daily/00logwatch /etc/cron.weekly

And basically we are done. If you want to test if it has worked, execute:

/etc/cron.weekly/00logwatch

Take care!