Our Server IP is cleaned, no spamming on the IP found/No issues. All records are correct however we're still seeing emails from the domain/ip sent to the below getting timed out/failing. Our client thinks its us. I've checked our IP in the PBL as well as on Symantec's site, found no issues.
IP Address is 199.103.61.10
Sample of the bounced messages are below.
HoMin.Lee@vaughan.caDelay reason: H=cluster4a.us.messagelabs.com [54.165.145.171]:SMTP error from remote mail server after RCPT TO:<HoMin.Lee@vaughan.ca>:421 Service Temporarily UnavNo action is required on your part. Delivery attempts will continue for sometime, and this warning may be repeated at intervals if the message remainsundelivered. Eventually the mail delivery software will give up, and whenthat happens, the message will be returned to you.---------------------------------------------------------------------------------------------