The automatic package builder Xi has moved to system within the Dovecot
infrastructure. This also means that the repositories are available at a
new host name: xi.dovecot.fi. The old host name still works and is a
CNAME pointing to the new venue. I expect the old domain to be active
for years to come. So, there is no need to update your
/etc/apt/sources.list right away. Still, it is a good idea to do so.
I've updated the wiki accordingly.