Gmail emails are not received

Hello dear friends,

I have verified that I can not currently receive emails from gmail.
I have tested with hotmail and sending and receiving work properly.
Also, there is a client of our business that indicates that he has not received an email that we have sent him. I would like to know if I can access a log to verify the mailing.
I would like to know if the configuration I have is correct and what procedures I should follow if necessary.

I thank you very much in advance.

Greetings.