Its generally considered bad form to make use of the map BLOCK, LIST function in this manner - This is generally because, the real power of this function lies in the return of a list, each element having been evaluated by your BLOCK or expression.

This has even been addressed by faq_monk at What's wrong with using grep or map in a void context? :-)

 

perl -e 's&&rob@cowsnet.com.au&&&split/[@.]/&&s&.com.&_&&&print'