Every RIPE LIR (Réseaux IP Européens Local Internet Registry) must have an abuse@
account and based on the RFC 2141 the webmaster@
(http), postmaster@
(smtp) or hostmaster@
(dns) addresses are used by most (all?) SSL Providers.
So if you don't want to be an LIR and don't use certificates, you are mostly free to set your mail addresses any way you want.