DNS Reverse resolution Command nslookup

Background

User A Domino mail server was hung up and a new one was built, resulting in a pile of back letters. Here are two of these questions

Question one:

No route found to domain xxx.com from server xxx/xxx. Check DNS configuration.

"Issue Tracking"

1. Server Side--run--cmd

2. nslookup

3. Set TYPE=MX

4. Enter xxx.com to discover that this domain name is not resolved at all.

DNS configuration address problem was found, changed the DNS after the external network is normal.

Question two:

Was wasn't delivered to: [email protected]

because:554 Message relaying denied for security policy.

"Issue Tracking"

Input Address: http://www.spamhaus.org/query/ip/xxx.xxx.xx.xx

Found to be pulled into the blacklist, only a step by step representations.

Report:

Check if the message is blacklisted

http://www.spamhaus.org/

Http://mxtoolbox.com

DNS Reverse resolution Command nslookup