sendmail a asi DNS problem

[zaboj na vseedu.vse.cz]

Vazeni, resim problem se sendmailem a jsem uz z toho pomerne nestastny.
Predne sendmailu potrebuju kuli openmailu a tudiz se ho nemuzu uplne zbavit.
Symptom je, ze mail prichazi nekolikrat. Pri loglevel 65 to 
_vetsinou_ vypada nasledovne (kde domain je moje domena a user nejaky user):

Jan 30 12:07:54 mail sendmail[21445]: MAA21445: --> 250 <xxx na yyy.cz>... Sender ok
Jan 30 12:07:54 mail sendmail[21445]: MAA21445: <-- RCPT TO:<user na domain>
Jan 30 12:07:54 mail sendmail[21445]: MAA21445: --> 451 <user na domain>...
 domain: Name server timeout
Jan 30 12:07:54 mail sendmail[21445]: MAA21445: --> 050 <user na domain>...
 Transient parse error -- message queued for future delivery
Jan 30 12:07:54 mail sendmail[21445]: MAA21445: --> 451 <user na domain>...
 domain: Name server timeout
Jan 30 12:07:54 mail sendmail[21445]: MAA21445: --> 250 <user na domain>...
 Recipient ok (will queue)

pricemz nekdy je vsechno OK - bez Name server timout a 
Recipient ok bez "will queue".

Kdyz je to spatne, pak se to ulozi do /var/spool/mqueue a sendmail se to
snazi dorucit opakovane - coz se mu uspesne dari (v mboxu je to vickrat)
a pak najednou prestane.
Ve /var/spool/mqueue/msg je napsano domain : Defered.

Tusite nekdo cim by to mohlo byt? Jake jmeno se snazi sendmail po RCPT zjistit?
Dekuji,
P.Zaboj