Recommendation letter after 1 month?

Question

I am applying for a US PhD program. One of my recommendation letters arrived 1 month late.

Should I

1) contact the department

or

2) contact potential supervisors to kindly ask them to consider it, given that the delay was out of my control?

or

3) do nothing?

Answer 1

Contact the department immediately and provide evidence that the letter itself was delayed. Then cc your referee on the correspondence.