an easier way would be to go to file>identities>add identity and then import the remaining email accounts into the new identity.
That's how I did it. I have 43 email acounts for advertising my business (in my signature), depending on where it is in the country.
EDIT: also, Ian, I tried PMing you but it wont let me for some reason. Please check out the
'sponsored sites' section on my site, and let me know if you'd be interesed. Not really sure if you would as it seems the majority of this site is based in the UK.