Have you added a Cw line to /etc/sendmail.cf?  If not try something
like:

Cwlocalhost foo.bar.com.pl bar.com.pl

This is a list of domains that are considered local.

 == Roland
 == http://www.imrryr.org/~elric/

On 903721268 seconds since the Beginning of the UNIX epoch
Adam Ciarcinski wrote:
>
>Hi,
>
>I've added the following to DNS (mydomain.hosts):
>
>@	IN	SOA	foo.bar.com.pl. admin.foo.bar.com.pl. (
>		1998082103
>		21600
>		7200
>		1209600
>		172800 )
>	IN	MX	10 foo
>
>localhost	IN	A	127.0.0.1
>.....
>
>When I send e-mail to user@bar.com.pl from foo.bar.com.pl, admin gets
>error message via e-mail, with:
>
>.....
>554 MX list for bar.com.pl.  points back to foo.bar.com.pl
>554 <user@bar.com.pl>... Local configuration error
>.....
>
>When I send e-mail to user@bar.com.pl from different host - everything's
>fine.  Could anyone help me?
>
>	regards
>
>		- Adam
>