Re: Nameserver calls - libesmtp problem?

[Brian Stafford <brian stafford uklinux net>]

On Wed, 20 June 22:23 Albrecht Dreß wrote:
| Hi all!
| 
| I am afraid that I have a problem with unwanted nameserver calls from
| balsa 1.1.6, compiled with libesmtp...
|
| I suspect that balsa (or libesmtp?) initiates a dns call.

Correct!  This is how libESMTP resolves the domain name of the
submission server to its IP (v4 or v6) address.  All modern networked
applications are expected to work like this.

In fact libESMTP goes further, if DNS specifies multiple A records
against the same host name, libESMTP will try to connect to each host
in turn.  When it connects, it checks the SMTP greeting to verify that
the server is not temporarily off line.  If either of these steps fails
it backs off to the next server in the list.  DNS rotates the order
the A records are returned on each query, so this achieves both
redundancy and load balancing for virtually no programming effort.

| Before I dig into the sources: can anybody confirm this problem
| (feature? bug?), 

I don't consider this to be a problem or a bug.  It is a correct
implementation for an internet application.

| and does anybody have an idea how I cat get rid of that
| behaviour?

Check your settings in /etc/resolv.conf and /etc/hosts.  If these
are correct and /etc/hosts has an entry for at least localhost
the DNS query should be eliminated.  Alternatively try setting the
host name to "127.0.0.1:25" but this might depend on the implementation
of gethostbyname() on your system and will certainly break if you
are using IPv6.  Use of IP address literals is generally to be
discouraged.

Regards,
Brian Stafford