ip blacklisted removal request

Good morning,

We have som trouble to send emails to some domains protected by MessageLabs.

Here the part of log. Our ip is 78.4.29.24

  Waiting for protocol to start...<-- 220 server-5.tower-201.messagelabs.com ESMTP
  --> EHLO mail.trevispa.com<-- 250-server-5.tower-201.messagelabs.com<-- 250-STARTTLS<-- 250-PIPELINING<-- 250 8BITMIME
  --> MAIL From:<xxxx@example.com><-- 250 OK
  --> RCPT To:<xxxx@example.com.au><-- 250 OK
  --> DATA<-- 354 go ahead
  Sending <xxxxxxxxxxxxxxxxxx\pd35013664479.msg> to [216.82.242.45]
  * Socket error 10054 - Connessione reimpostata dall'altro lato.
  Errore di scrittura socket
  Socket connection closed by the other side (how rude!)
  * Socket error 10053 - Connessione interrotta.
  Connessione chiusa

Best regards and good job