Erro ao entregar e-mail. URGENTE

Ola galera,

Estou com alguns problemas em nosso servidor de e-mails.
Ao enviar e-mails para alguns domínios eles nos retornam com esta msg, poderiam verificar oq acontece e me me orientar dizendo como proceder.

grato pela atenção
filypepereira

Hi. This is the qmail-send program at americanadigital.com.br.
> I'm afraid I wasn't able to deliver your message to the following
addresses.
> This is a permanent error; I've given up. Sorry it didn't work out.
>
> <[email protected]>:
> Connected to 64.239.74.30 but connection died. (#4.4.2)
> I'm not going to try again; this message has been in the queue too long.