After several attempts, I cannot get kmail to work correctly with mails that
existed in the 12.3 version. Selecting an email to read results in a VERY
long wait (think hours). Sometimes, the message appears in a few minutes or
so but others are in what is essentially an infinite wait.

Since this is demonstrably an artifact of having existing mails prior to the
12.3 -> 13.1 update I strongly suspect that the indexing is all fouled up.
Is there a way to force the kmail indices to be rebuilt?

Will Honea