When I send to a data extension, I get the 'de-duplicate subscribers by email address' checkbox, which is great.
However, you can't do that when sending to a data filter.
Anyone know how you might? Maybe using Exclusion AMPScript?
You can create an automation that first runs the filter and pushes the results to a sendable data extension. You could then de-dupe your send to that sendable data extension. Both steps could be added to the same automation, so running it would refresh the filter results in the sendable data extension, and then it would do your send.