Privet. Configurirah sendmail na edna mashina, koqto se
 qvqva mail server na domain. V DNS-a vsichko e tochno. Na
mashinata ima pusnati pop3 i smtp service ot interd.conf.

 Izprashtaneto na pisma raboti mnogo dobre, no mashinata ne
 moje da poluchava pisma. Pri opit za izprashtane na pismo
 kum tozi domain pismoto se vrushta ot mailer damon-a sus
slednoto suobshtenie za greshka:

Message from  yahoo.com.
Unable to deliver message to the following address(es).

<xx@xx.com>:
 Sorry, I couldn't find a mail exchanger or IP address.
(#5.4.4)

 Na kakvo se dulji tova. Predpolagam na mashinata na koqto e
 sendmail-a trqbva da se pusne oshte neshto, ili e vupros do
configurirane na sendmail. Nadqvam se da mi pomognete!!!

Spored men nqmash setnat mamail exchanger kam <xx@xx.com>
proveri dali e taka 
nslookup -sil 
set type=MX
xx@xx.com

trqbva da ti varne slednoto
Non-authoritative answer:
xx@xx.com      mail exchanger = 5 mail.xx@xx.com.

Authoritative answers can be found from:
mail.xx@xx.com      nameserver = ns.xx@xx.com.
mail.xx@xx.com      internet address = xx.xx.xx.xx

Proveri parvo tova

 ZNachi spored ne e zadaden MX zapis za tozi domain v DNS
 servera, taka li da razbiram, ili ne e pusnata dadena
programa na samata mashina koqto otgovarq za poshtata.

Pravilno si me razbral
ako e taka probvay s foward kam mail servera na ISP-to ti

 sega zabelqzah che sum izpolzval za MX host.domain.com i sum
zabravil da sloja . sled com