Default exim dns rbl settings

[SEO Guru]

I was looking at /etc/exim.conf and I noticed

RBL_DNS_LIST=\
       b.barracudacentral.org : \
       zen.spamhaus.org!&0.255.0.0

Why is this !&0.255.0.0 part of it?

I override this settings in my own /etc/exim.strings.conf.custom can it break something if im not using it?

 

[DrWizzle]

I believe the !&0.255.0.0 is a legacy bitmask. Shouldn't break anything if you omit it. And if you create your own custom file, that overrides anything in /etc/exim.conf anyways.