[sf-lug] sf-lug.{com,info} --> www.sf-lug.org (canonical)

[Rick Moen]

Quoting Daniel Gimpelevich (daniel at gimpelevich.san-francisco.ca.us):

> On Fri, 2016-01-08 at 14:03 -0800, Rick Moen wrote:
> > If you wish to do a test, map an FQDN in public DNS to that IP.  Make
> > sure that DNS propagates so that, e.g., my DNS doesn't have an earlier
> > IP in cache.  Then try to send mail to danielg4@[FQDN] .
> 
> Simply an A record?

That's sufficient.  

RFC-mandated behaviour (RFC 5321 sec. 5) for delivering mail is:

1.  Look for an MX first.  If there are multiple, try them in order of 
published priority number, lower numbers first.

2.  If no MX exists, use A or AAAA as fallback.
https://en.wikipedia.org/wiki/MX_record#History_of_fallback_to_address_record

If you don't know the details of DNS, there is a lot more that I'm not
going to remember to include here.  For example, as with NS records,
it is not valid to point an MX to a CNAME record, nor to an IP address.

(I've seen both errors in the field.  They cause deliverability
problems.)

If you will be maintaining zonefiles, I urge studying some DNS
documention, to avoid similar pitfalls.