Problem with sending emails to other domains

We are experiencing problem with outgoing emails to other domains. The emails within our domain work fine. We are getting this message on the server: " Router: Failed to connect to SMTP host DRESSER.COM because Server not responding"

We are using Lotus Domino Server 5.0.12.

Is this a DNS problem or something with the SMTP server is wrong?

Thanks.

You are telling that you are getting some kind of error message while trying to send Email from other Domain. first of all make sure that the Email address is proper. if it is correct then again make sure that the DNS setting which you have applied for DRESSER.com is proper. The reason may be it might resolve toward some different server that isn't hosting that mailbox which you are using.