[cobalt-users] Qube 2 - SMTP Relay

[Malcolm McLeary <mmcleary@xxxxxxx>]

Hi Guys,

As I understand it, the Qube 2 accepts email if the recipient has a user
account or an alias email account, or if the sending host (your client
computer) is trusted to relay outgoing emails to another domain. These
trusts are defined by host or domain names, as well as by IP addresses and
networks. 

This is working fine under normal conditions, but if the network gateway
goes down LAN Clients get "time outs" when trying to send email.

After a few trials it turns out that its sending email to external
recipients which causes the "time out".  It would appear that sendmail is
trying to resolve the recipients domain BEFORE accepting the mail from the
client.  

Is this "normal" behaviour?

It's pretty much unacceptable to the users.  They accept that there may at
times be an ADSL failure, but this shouldn't prevent them from passing mail
to the Qube for it to send it when the connection is re-established.

I don't understand why sendmail needs to do DNS Lookups when deciding
whether to accept a message from a client ... the lists of domains/addresses
for "receive" and "relay" are effectively hardwired so I'd expect that DNS
Lookups are only necessary when actually relaying the message.

Is there a way to disable this checking?

Cheers,  Malcolm