Assuming there are four different work spaces,
how to make sure that the leads receive only a single email despite they exist in one or more work spaces.
Does this work:
Step:1. Send emails to the leads under work-space A.
Step:2. Exclude the leads of work-space A in the next run.
Step:3. Exclude the leads of A,B.
Step:4. Exclude the leads of A,B and C work-spaces.
Continuing what Josh said, leads don't exist in workspaces. Workspaces have access to lead partitions. Leads sit in lead partitions. You can give workspaces access to multiple lead partitions. A lead can only reside in a single lead partition (as well as the default partition, which contains all leads). If you have some sort of purposeful duplicate process, you can hide a lead partition from all but one workspace (including the default workspace) and have it contained in that partition as well as a duplicate in another partition. So I guess before we can provide the best answer, is this a single lead that exists in a dedicated lead partition, where multiple workspaces have access to it?
Communication Limits probably your best bet.
I assume here you mean that each Workspace has a corresponding Lead Partition?