Cook the pasta in a large pot of salted, boiling water. When it's al-dente, add the frozen corn to a big colander and pour the hot pasta and its water right overtop to drain and thaw the corn. Rinse with cold water until cool.
Meanwhile, toss the vegetables, basil and capers with salt in a large bowl. Add the pasta and corn, plus most of the feta (reserving a bit), mayo and pepper. Toss to combine. Top the salad with more feta, if desired, and serve.
Notes
May be made up to 24 hours in advance, simply omit the tomatoes until ready to serve.