External emails are staying in the message queue

[gwhitson]

All emails sent outside of the domain are staying in the message queue with following error.
451 4.4.0 primary target ip address responded with "421 4.2.1 unable to connect"

Thanks

 

[APPI007]

check if the you have more than 4GB of space all disks where you have exchange logs,database and any exchange related stuff as u need atleat 4GB free space for exchange 2007

 

[gwhitson]

Thanks for the reply, The problem truned out to be with our firewall

 

[APPI007]

ok