virtual/search folder merging the contents of several real folders?

Hi,

From time to time I need to peruse email that is archived in several related folders, which may not reside on the same server. I have been using a search/virtual folder for that, with the search defined as follows:

* Select specific folders -> target folders
* Match any of the following
  Size in Bytes is greater than or equal to 0.00 kB
  <2nd criterium left empty>

This works though it does throw an "akonadi_search_agent" resource not found error nowadays.

However, I've just linked it to the occurrence of the 1452 DB error: I started getting that message again on a system where I hadn't seen it for a long time, after creating such a search folder. They stopped appearing after I had deleted the search folder.

Is there another way to achieve what I'm trying to do here, without getting those pesky errors?

Thanks,
René