Hi Everybody,

The last week, a customer did call to me because he has an trouble with a network scanner and his mail server.

Basicly the problem was that when he want to send the scanned image to his mailbox, the scanner shows an error that says something like: "Failed to connect to the SMTP server... timeout".

The scenary:

The mail server is in the lan only with an Public IP, his default gateway is the firewall.
The users are in the same lan with static privates IPs, his default gateway is the firewall too.

When I try run an telnet to SMTP server on port 25, the SMTP banner appear after 50 seconds.

I think that the sendmail is trying to get an reverse lookup for the lan IP and the DNS server can't give him that information. I resolve the problema adding the printer IPs to the /etc/hosts file in the SMTP server.

The question:

In sendmail, how can I disable the reverse lookup to the client IP address?

Thanks for all and sorry for my bad english...

Best regards,

Strong1983

If the problem is resolved, why disable reverse lookups ? You will be open to much more junk mail. Do you have a DNS cache ? ( Bind can be installed on any system as a DNS cache only ). It would make the lookups faster.

Perhaps your email server has a filter on it for image files, blocking them ? Bet it does, which would explain your original problem.