either
a) you've been using your ISP email for a long time, can't really change your email address
either
a) you've been using your ISP email for a long time, can't really change your email address
b) you don't want to migrate because it's a hassle/you don't know how to
...
if you want to, you could also buy a domain name, set up the mail exchange servers to point to your own email server / google apps
^- what i've been doing... my own domain name (eg paperwastage@somedomain.com... and using google's front/back end)