You might want to look up if and case functions in FileMaker help.
If(Status = "Mail Swap" and Modified Date ≤ ( Get(CurrentDate) + 30 ) ) ; 30; "No" )
I'm assuming that Modified Date is a field of type date.
Thanks PMJ it got me where I wanted to be. I thought I tried your formula but guess I was missing it. You did end up with an extra ) between the 30's but I solved it.