Re: [Exim] Verisign pulls a fast one

On Wed, Sep 17, 2003 at 07:16:03PM -0400, Walt Reed wrote:
> Many mail servers fall back to the A record when no MX exists.
> BTW, anyone have an ACL that rejects mail when the sender envelope
> domain does not have a valid MX record?

I wouldn't recommend this. It's perfectly legal for DNS zones to not
have MX records and still send and receive mail.
An MX record simply allows you to have a smaller set of hosts receive
all mail for that zone, instead of each individual machines receiving.