Since I run a hosting business, my server is configured correctly.
omniweb-5.6-crash@omnigroup.com
SMTP error from remote mail server after RCPT TO:<omniweb-5.6-crash@omnigroup.com>:
host omnigroup.com [198.151.161.1]: 450 <omniweb-5.6-crash@omnigroup.com>:
Recipient address rejected: Greylisted for 5 minutes:
retry timeout exceeded