Which is easier to read
yourrealname@yourdomainname.com.au
or
YourRealName@YourDomainName.com.au
It is a rhetorical question; What would the world be like without rhetorical questions?
It is fine to capitalise your domain name and email address wherever you use them and I highly recommend it, especially if you have a domain where two words have the same joining letter e.g. imagineengines compared to ImagineEngines. It makes it easier to read and also makes it stand out a bit in people's minds since it isn't done a lot.
TRIVIA: This is known as CamelCase - read more
Stuck? Lost? It isn't a capital offense, Lodge a support ticket