Question : DNS A-Records and MX-Records clarification

Hello experts, i am kinda confused here so i seek clarification. This is the setup at my ISP DNS management site.

A Record                         IP Address

mail.domain.com              xx.xxx.xxx.xxx

MX Record                       To

[email protected]       mail.domain.com

My question is, what is the "mail" operator do? Is it a standard, can i place any word i want, do i need to place a word before the domain? Why cant it be "www"?

I am confused because mail.domain.com is not an FQDN for any of my servers. Still, public mail gets delivered and sent successfully from users in my network.

thanks in advance and sorry if the question is kinda stupid.
   

Answer : DNS A-Records and MX-Records clarification

DNS is just a lookup mechanism.

It resolves a name to an IP address. The name doesn't have to actually match any machine - in the case of MX records I actually recommend that a generic name is used.

Therefore as long as mail.domain.com resolves to your external IP address and you are routing port 25 traffic to your email server then email will be delivered.

Simon.