I can report I had exactly the behavior described here (about the mail dispatcher being offline) and akonadictl restart temporarily fixing the issue, on a complete fresh install of Kubuntu 11.10 Oneiric Ocelot with KDE 4.7.2 (from the backport PPA).
I configured Kmail 4.7.2 from scratch so there was no migration.
I don't think this is a migration issue.
I can report I had exactly the behavior described here (about the mail dispatcher being offline) and akonadictl restart temporarily fixing the issue, on a complete fresh install of Kubuntu 11.10 Oneiric Ocelot with KDE 4.7.2 (from the backport PPA).
I configured Kmail 4.7.2 from scratch so there was no migration.