Migrate email domain from old .yyy to .zzz over time using aliases

Migrate email domain from old .yyy to .zzz over time using aliases

Hi,

I have an email domain that I've used for a long time that I'd like to migrate from.

I have purchased a new domain and over time would like to use the new user@newdomain email address.  

I would prefer to have the alias point to the old (in use) address so that I can cancel the old domain.  The alias section in the console has some "this is a one time irreversible action" warnings, so I'd like a clear transfer path that doesn't have me delete data/relationships that are hard to replace.

Thanks,
David