[ILUG] sendmail

[Niall O Broin]

On Thu, Jun 20, 2002 at 05:10:11PM +0100, Declan Grady wrote:

> When I dialup to iol I get a fixed ip addy.
> Iol's relay(s) then dump my mail to my sendmail to handle.. no problems
> there.
> 
> However, I would expect to receive mail direct to my box form other sources,
> but I dont seem to. Everything comes from relay1.mail.iol.net or
> relay2.mail.iol.net.
> 
> I do have some ipchains rules, but I dont see anything obvious in the
> syslogs to show denied connection attempts.
> 
> If I do a 'dig mx nuvotem.com' my fixed IP is listed with the highest
> priority, so I would expect to be receiving mails while I'm connected.
> 
> Am I missing something ?

Probably :-)

I'm guessing that relatively speaking, your fixed IP is more often than not
unreachable. So mostly sending mail servers will fail to reach it, and will
use instead one of the backup MX and (now comes the guessing part) they will
cache this for a period of time (the guessing here is becuase I don't know
how caching of MX to A rec. is done, or if it's done at all. The cricket
book is silent about it, but domain data is cached -> MX records are cached.
However, is the fact that we had to use a particular MX last time cached, or
is a fresh lookup done each time - I don't know. 

But if that result is cached, it would go a long way to explaining your
problem.




Niall