Why does the mail function take 60 seconds to complete?

Question

PHP

The mail function takes more than 60 seconds to complete. Usually 60.4 somewhere. It feels like there's just a delay somewhere.
How and where to dig?

UPD:
mail('мой@адрес.почты', 'test', 'body');

Answer 1

Most likely, the server resolves the DNS name of the client to the IP address - and cannot, so it is waiting for a timeout.
Second option: You are trying to push the letter to the main relay, but he does not answer. And after a timeout - the letter is thrust into the spare relay.
Third option: GreyListing is running on the server.
Specify on which computer you are running the mail function; and which server you are connecting to.

Answer 2

Any delay in network traffic - immediately turn on the sniffer and read (understand) the log to understand the whole process and determine the cause of the delay.