Grey List/ Black list

[aquariu8]

Im interested to know what this list is that ive heard mentioned here

 

[dcc420x1]

From wikipedia

A DNS-based Blackhole List (DNSBL) or Real-time Blackhole List (RBL) is a list of IP addresses published through the Internet Domain Name System (DNS) either as a zone file that can be used by DNS server software, or as a live DNS zone that can be queried in real-time. DNSBLs are most often used to publish the addresses of computers or networks linked to spamming; most mail server software can be configured to reject or flag messages which have been sent from a site listed on one or more such lists. The term "Blackhole List" is sometimes interchanged with the term "blacklist" and "blocklist".

A whitelist is the opposite of a blacklist (ie a list of approved sites), and a greylist would be somewhere in between

 

[essellar]

In this case, it's about the outbound mail. If you try to send too much out (there is a 100/hr limit, but since mail is queued and not sent in strict real-time, it's never safe to assume that you can actually send 100/hr since more than 60 minutes worth of you sends may hit the top of the queue inside a given hour) or your mail looks spammy to the outbound filter, you may be greylisted (outbound mail is temporarily blocked, but you can have the block lifted). Keep it up, or fail to fix the problem that got you greylisted, and you'll be blacklisted (outbound is permanently blocked and the block will not be lifted). More serious infractions (fraudulent or phishing mail, etc. -- things that, if they were part of your website, would be a violation of the terms of service) will earn an account suspension rather than just affecting your ability to send email.