What happens if professor submits a recommendation late on CA?

Does Common App allow them to even submit one late (past the March 21 transfer deadline) or will they have to submit it by mail? Will universities no longer consider your application if it’s submitted a week and even 2 weeks past the deadline? I’m just worrying because one of my professors might submit it maybe even 2 weeks past it :frowning:

Sorry March 1st not 21st!