consumer IP space is really a problem for outgoing mail. at the very least, all the majors will add spam points to your messages and so your mail is a lot more likely to be bulked. even resold IP space at large colos is treated that way by default, and it causes heartburn for businesses. just having reverse DNS isn't good enough, either, because if it has a name that "looks" like dynamic IP space, that can also get your mail treated with prejudice. it's best to own your own reverse DNS so you can give it a realistic look.
you can try to work with the major ISPs to get your IP(s) whitelisted, and try to convince folks to take them off their no-no lists as well, but that can be very time consuming and you'll have mixed results. bottom line is, check out the reputation of your IP space before buying it. you don't want the problem to start with. ...lori
