Problem with installing LetsEncrypt on Nginx Centos 7 after installing iRedMail

So I installed iRedMail for my mail server, after that I wanted to install LetsEncrypt but it gives me errors.

IMPORTANT NOTES:
 - The following errors were reported by the server:

   Domain: mail.placetoknow.com
   Type:   unauthorized
   Detail: Invalid response from
   http://mail.placetoknow.com/.well-known/acme-challenge/xZnfjqAedEiwkmbe2BWNWMT1ul-6MAyypleQOxeo3Ww:
   "<html>
   <head><title>404 Not Found</title></head>
   <body bgcolor="white">
   <center><h1>404 Not Found</h1></center>
   <hr><center>"

   Domain: app.placetoknow.com
   Type:   unauthorized
   Detail: Invalid response from
   http://app.placetoknow.com/.well-known/acme-challenge/C83_ljkYsC2Dfue6X4x0uK3ySZZS2k35X6vfAnC1oEY:
   "<html>
   <head><title>404 Not Found</title></head>
   <body bgcolor="white">
   <center><h1>404 Not Found</h1></center>
   <hr><center>"

   Domain: www.placetoknow.com
   Type:   unauthorized
   Detail: Invalid response from
   http://www.placetoknow.com/.well-known/acme-challenge/GT-feTfFHHlRYl6wgQsXve8ji9JxpveJbIKkW4M4VLo:
   "<html>
   <head><title>404 Not Found</title></head>
   <body bgcolor="white">
   <center><h1>404 Not Found</h1></center>
   <hr><center>"

   To fix these errors, please make sure that your domain name was
   entered correctly and the DNS A record(s) for that domain
   contain(s) the right IP address.

I really don’t know how to solve this problems. Thank you in advance