Looks good.
You may find the mail command doesn't send it outside of your box tho'
You could use nail..
eg..
postrotate
/usr/bin/nail -s "Dansguardian access.log" -a /var/log/dansguardian/access.log.1.gz -A andrzej
www@site.org < /root/dg.msg
endscript
It requires detailing the -A account used and a message file to provide text fot the email body.