What Gertrude said.
I have several domains, all of which forward (some via Spamcop) to my "real" ISP address. Nobody (but nobody) has that address.
When I change ISP, all I have to do is go into the control panel of the "master" domain and change one setting. I've done that three times now, and it's dead easy.
I pay under £7 for two years service on each domain.
The main one is just
[email protected] - nobody has a problem remembering that. I also have
[email protected] for those who forget, and put .uk on the end.
The great advantage is that it's totally transparent, the address is easy for my contacts to remember, and I don't have all the faff of webmail etc.