content/blog/mail_server_alpine_postfix_dovecot_tutorial.md: use dns as highlighting language as listed here: https://gohugo.io/content-management/syntax-highlighting/

content/blog/mail_server_alpine_postfix_dovecot_tutorial.md

@@ -141,7 +141,7 @@ choice.
 An MX record denotes that your domain is used to send and receive email, and tells other MTAs the domain name of your
 mail server. We will use `mail.domain.com` for your MX record. For instance, my MX record looks like:
 
-```bindzone
+```dns
 revsuine.xyz.                    14400 IN MX    0 mail.revsuine.xyz
 ```
 
@@ -153,19 +153,19 @@ same as the IP address of `domain.com`, or an A record if the IP address is not
 
 I use a CNAME record because the IP addresses of `mail.revsuine.xyz` and `revsuine.xyz` are the same, so my record is:
 
-```bindzone
+```dns
 mail.revsuine.xyz.               14400 IN CNAME revsuine.xyz
 ```
 
 If you use an A record, your record may look something like
 
-```bindzone
+```dns
 mail.domain.com.                    14400 IN A     ip.address.here
 ```
 
 If you use IPv6, you should also add an AAAA record, e.g.:
 
-```bindzone
+```dns
 mail.domain.com.                    14400 IN AAAA  ip:address:here::
 ```