[Dovecot] Migrating domain with diferent default_pass_scheme

[Oli Schacher]

Hi Emilio

For this purpose we used dovecot proxy & mysql with a view that would
prepend the pass scheme depending on if an account is already migrated
(pointing to old or new IP):
create or replace view v_proxy as concat(if(proxyhost='<ip of new
server>','{MD5}','{PLAIN}'),<old or new password>) as password,
[... other fields you might need...]
from accounts;

Basically you ignore the default_pass_scheme and let mysql prepend the
correct scheme based on whatever property you like, in your case the
domain name. You could do this in the target database directly but if
you need the different pass schemes only while migrating (and update the
old passwords to the new format) I'd recommend using dovecot proxy so
you don't have to change your target user table. This also has the
advantage that users don't need to set new hostnames in their clients -
you simply point the hostname to your dovecot proxy and after the
migration is completed point it to the new system.

hth
Oli