== greylisting can get your mail server blacklisted == 

 just a note about this. i wonder if others feel the info that "greylisting might result in your mail server being blacklisted by some spam-control services" might belong in the article's disadvantages section. [I can only relate my own anecdotal experience and do not have the technical knowledge to participate on this article as an author.] 

 i have a very low-traffic domain and host a very small discussion list (mailman) and several mail accounts on the mail server. because I need to receive mail from legitimate unknown parties without forcing them through any kind of validation procedure, i cannot rely solely on whitelisting so i use greylisting to eliminate 99% of all spam successfully. 

 however  one of my discussion list subscribers forwarded a note from his ISP that he can no longer send to or receive mail from my server. his ISP uses "backscatterer.org" (see Backscatter) as one RBL source and a test on my mail server's IP address on backscatterer.org says: 
 "This IP  IS CURRENTLY LISTED in our Database. Please note that this listing does not mean you are a spammer, it means your mailsystem is either poorly configured or it is using abusive techniques.If you don't know what BACKSCATTER or Sender Callouts are, click the links above to get clue how to stop that kind of abuse." 

 This org considers sender callouts to be "abuse". They keep one's server on the blacklist for four weeks and if one is still employing greylisting they just re-list you. The only way to get delisted quickly is to first kill your sender callouts and to PAY backscatterer.org 50 euros (!!!). This is after they first punish you for doing something that is fairly standard, blaming you for the way spammers operate, and even insulting folks who employ greylisting on their mail server. (Their Contact Us page reads: "There should be no need to contact us:  We have heard all possible excusions why people think they can not stop their systems backscatter or doing sender callouts. If you have chosen to be a lazy or selfish netcitizen letting your system backscatter or doing sender callouts you perfectly match listing criterias. Your recipients and we are tired of all the fake bounces, misdirected autoresponders and verify calls wasting our resources, and therfore you got blocked." Personally, I think they are lazy and selfish netizens for putting up such a poorly written page [if you want to write in English, spend the time or money to make it literate!] and for blacklisting folks for having a perfectly legal setup and then CHARGING to be removed only if you set up your mail server the way THEY want. 

 Back to the Wikipedia article, I would not ask that backscatterer.org be trashed for the horrible organization it is, but I do think that in the Disadvantages section some note should be made of the disadvantage to the mail host who becomes blacklisted because of sendouts, and also the potential for DdOS attacks against the owner of an email address that was used in forged spam, such as backscatterer.org claims can happen on their page at http://www.backscatterer.org/index.php?target=sendercallouts