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

There are no name translation tables for individual e-mail addresses.  For
example, you have your e-mail forwarded to a different account, but someone
else on your ISP may not.  DNS routing tables only work for the domain name
itself:  for instance, my ISP is stargate.net.  That translates to
209.166.165.174.  If I had mail forwarding services, the sender would send
mail to the address I specify.  The forwarder sees that the e-mail came to
your address and isn't supposed to stay there, and so it then shuttles the
e-mail to your real address.