Hello !
I don't think it worth doing by hand, too much work. I was just thinking of doing an alias, so there would not be pure-data.org mailboxes, all mail sent to a pure-data.org account would be forwarded to an account that the user sets.
In plone everyone has to have an email who is member. Is this true also on the old pure-data site. So can you compile a list of emails, so when the time has come we can sent all of them a mail to join the new site.
did you have mailboxes on youre site for members ?
btw. there is a mailboxer product for plone, where poeple can make maillinglists, should we use that. The drawback is that the administration could rise a lot... if they make mistakes and use it for spaming...
mfg winfried