Comment 6 for bug 997943

One action seems atomic, but multiple actions are done out of sync and in parallel --- this is OK, as long as none of these actions removed the mail. As soon as this is the case, some of the defined actions may work on something removed without noticing. Leading to empty mail copies.

All actions done on one Mail have to be threatened as one transaction.
All actions done on one Mail have to be done one by one, as defined by the filter.

In the above case:
1. Open transaction
   Start filtering
2. Copy the mail
   Make sure it is copied
3. Move the mail
   Make sure it is moved
4. Terminate the filter
   Close transaction

And for those telling me again it is done as defined, exactly one by one:
why does it move the mail *before* it is copied???