If your sendout is using contacts from your contacts database, then you can create sets of these which you can then apply to other sendouts.
Get all the desired contacts assigned to the appropriate trades
Click on Usual Suspects
Select Create New List From Current Sendout
Give it an appropriate name, probably something to do with the type of project and the location, such as Housebuilding - South East
In your other sendout, in the Contacts section click Usual Suspects
Point to get contacts from existing list: The selection will appear to the side of this menu
Click the appropriate list
This will then assign the contacts from the original sendout to the same trades in the current sendout
Note: Usual Suspects only works with database contacts - temporary contacts are sendout-specific.
It will only assign contacts to the same trade they were originally on. If the trade is not in the new sendout, then these contacts will be skipped. Cloned resources, even if they have the same name, are not recognized as being the same resource by the system, and so no contacts assigned to cloned trades will be brought across.