Hi @sunilshah,
Welcome to the Community, we are so glad you’re here!
Unfortunately, you cannot segment off of whether or not someone has been in a Flow at this time.
A potential workaround I would suggest is creating a segment off of all the Subject lines in your specific Flow emails . The segment will be created by adding What Someone Has Done > Received email > At least Once over All Time > Where Subject Line Equals _____ ( enter all of your subject lines for each flow message) AND Has Received email > Zero Times > Over All Time > Where Campaign name equals > _____ (enter all of your campaign names that you have sent out so far).
I suggest using the AND connector in this segment to ensure this segment is exclusive, meaning a user has to meet each segment criteria to be dynamically pulled into this segment.
For additional information on segments, I’d check out some of our documentation and have a look around the Community!
Thanks for being a part of the Community!
-Taylor