Subject: How does email routing work? Why are forwarders useful?

I use a forwarding service to allow receipt of email at a more mnemonic
address than my ISP offers and to relieve correspondents of ISP-change woes.

By doing so, am I causing my mail to take more hops and thereby using more
bandwidth to receive the same mail?

As I understand it, the DNS system uses large tables, cached at many locations,
to translate URLs to IP numbers.  But I suspect that my forwarding instructions
do NOT alter the DNS tables, and that my email must actually be sent -- in its
entirety -- to the forwarding service to be retransmitted.

Is that so?  If so, why?  Wouldn't adjusting the name translation tables get 
the same result using less bandwidth?  What is it I'm missing?

Re: How does email routing work? Why are forwarders useful?