Route53 can’t return redirects, it’s DNS system. You need to us Nginx.

Your problem seems to be the Nginx config file is incorrect. I’ve copied and pasted a working Nginx config I have and changed the domains for you

server {
listen 80;
server_name webmail.mywebsite.com;
return 301 https://www.gmail.com;
}
Your config appears to simply be missing is the word “return” in front of the 301.

If you want to redirect https then that’s a little more work, as you need a certificate and such. You can find examples online.