<p>When mail is received from a sender that the HyperOffice mail server does not recognize, HyperOffice may <strong>greylist</strong> that email. This will cause a delay in your mail being received.<br /><br />Greylisting (or graylisting) is a method of defending e-mail users against spam. A mail transfer agent (MTA) using greylisting will <strong>temporarily reject</strong> any email from a sender it does not recognize. If the mail is legitimate, the originating server will try again and the email is accepted. If the mail is from a spammer it will probably not be retried since a spammer goes through thousands of email addresses and can not afford the time delay to retry. </p>