I'm from Argentina and I know that some ISP, such as hotmail or other sites, block emails going out from our IP addresses, so now I bought a VPS in the US (from slicehost) with a fixed ip just for me and I want to know if for being a US IP will I have more chance to reach who I want instead being blocked?
Most emails blocked based on IP are either because that IP is on a known RBL (blacklist) or a company's own spam filters are blocking that IP (either through learning or through a "list" they subscribe to or are auto-updated with).
I'm guessing if it is a new public US IP you'll start out just fine. But be sure and use email practices that will help prevent you getting blocked in the future.
Things like allowing people to unsubcribe to emails and other techniques will help if you are mass mailing emails out. See here for help and suggestions: http://mail.google.com/support/bin/answer.py?hl=en&answer=81126
If you are just sending out emails as a typical company would to customers, etc. then I think you'll be just fine with what you have purchased.
Many ISPs register their dial-up and DSL/Cable modem pools in list of IPs that should never send emails. That way mail server can filter them out for spam knowing that they should never see valid emails from those IPs.
Also, if you don't have valid DNS (and valid reverse DNS and MX records), many email providers will block you as likely spammer.
I don't know for sure what everybody out there does, but I kind of suspect that IP-based email blocking isn't so much about geolocation, blacklisting Argentina or whatever, as it's about whether the IPs in question have been used for sending spam or are actively being used for doing so. Either way, if your IP number is just for you and nobody has been spamming from it, you should be okay.
Unless, of course, you start spamming from it, in which case you will be blacklisted promptly enough.
The question is, do they want you to reach them. Your US IP address might help you reach people inside the US but there are no guarantees and probably no addresses that aren't blocked by someone somewhere.
Some people are crazy and block just about everything. Some people do block geographically, but from their point of view this can seem reasonable if they are certain they won't receive email from certain locations (I have my doubts about this but... their email server their rules).
The thing to worry about with IP addresses if whether or not they have previously spammed. It's possible to get out of the "managed" DNS RBLs (for very small or crazy values of "possible" for some of the more extreme lists) but if a previous user of that address spammed from it and a bunch of sysadmins dropped the address into their local router's deny table then good luck with that one, I'm afraid.
Yes, IP addresses have different values. Addresses which were used by a spammer, for instance, are "tainted". They are in many blacklists and most blacklists are poorly managed or not at all so, in practice, these IP addresses have a lower value. Some people even suggested an evaluation system for IP addresses to reflect this.
The country of origin may be one of the inputs in a decision process: in the same way that some landlords do not rent to black people or some employers do not hire people with an arabic name. I remember a public meeting about spam, in Paris (France), where the AOL representative boasted "We blacklisted most of Africa".
But remember each destination site has its own policy and procedures so there is little chance that you will find a magic bullet, such as simply a change of IP address.
The different major ESP's use a lot of techniques to determine who to block and rate limit, but as others have mentioned it's usually independent of the geolocation of the IP. The most important thing for mail deliverability is reputation. Things that can impact reputation:
- how often your mails get marked as junk
- what you do with opt out requests
- do you have a constant stream of mail, or it sent in large chunks
- are you included on any publically available blacklists (spamhaus, spamcap, etc)
- do you have Domainkeys/SPF setup for your IP's
There are 3rd party tools like http://senderbase.org that you can use to help determine what kind of reputation your IP's have.
Also the major ESP's all provide support to help you with their deliverability to their customers (Hotmail's is located at http://postmaster.live.com for example.) Those teams can usually setup feedback loops with you so if a customer marks your mail as junk, they'll let you know so you can remove it from your lists.
There's another point to consider:
- IANA puts out (formerly) reserved IP ranges to RIR (Regional Internet Registrars, ICANN, RIPE, ARIN, ... - hope I didn't mix up the names).
- Good Sysadmins take care that unrouteable IPs can never ever reach their network, those (formerly) reserved IP addresses are such cases. Those IPs are blackholed on the firewall/router
- Lazy Sysadmins do that once in a lifetime and never ever update the list again
- Dutieful Sysadmins check the list regularly
- Really Lazy Sysadmins automate alerts that the blacklist needs to be changed thru some monitoring tool
- Brave Sysadmin take the automation a step further and generate their blacklist from a script so that no interaction is needed (I consider that brave because such things IMHO should be reviewed by a human)
Happened to us, we couldn't reach some US sites from european IPs becaus IANA put to /8 (IIRC) networks out in the wild which had been reserved up to that point in time. The people that ran the site didn't care about the blacklisted IPs and there was no way for us (and a couple of other people) to get to their site...