I haven't had this problem much on the local or my email account. However, other users on my server have a problem with getting greylisted.
I'm not sure what the problem is here. In the case of this log a SQL email account was sending to another SQL email account on my server. However, the sender was connecting from the WAN. I'm not sure what's causing this issue, and any help would be appreciated.
postfix/smtpd: NOQUEUE: reject_warning: RCPT from ...: 504 4.4.2 <OmegaStar>: Helo command rejected: need fully qualified hostname
postgrey: action=greylist, reason=new, client_name=... client_address=..., sender=..., recipient=...
postgrey: cleaning up old logs
postfix/smtpd: NOQUEUE: reject: RCPT from...: 450 4.2.0 Recipient address rejected: Greylisted, see (webpage)