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# 2 The Challenge

The main challenge for Argentina.Com is to achieve a dialup uptime of at least 99.95%, or less than 5 hours yearly downtime. Due to the high rotation and volatility in this business, things have to work correctly so the user does not switch -voluntarily or not- the dialup provider or the number he calls to connect. The dialup business involves a support structure to deal with the Telcos about telephony problems and quality of service, plus a technical structure where latency and packet-loss should be minimized due to the UDP nature of Radius and DNS, and where recursive DNS should always be available.

This also implies having a high uptime in the POP3 and SMTP services, and in the webmail. For POP3 and SMTP we estimated the need for an uptime equal to the one for dialup, whereas for the webmail we could live with 99.5% which means around two days of yearly downtime.

We decided to migrate the email to a proprietary, opensource architecture which should be horizontally scalable, and whose antivirus and antispam infrastructure should support more than just one type of mailstore or back-end.

The rough competition in the free email market, mostly due to the recent improvements introduced by Hotmail, Yahoo and Gmail, made it necessary to design the new system with at least 300M user disk space, but at a cost lower than 3 US dollars per GB with some degree of redundancy. Bear in mind that rackmountable hardware is hard to find in Argentina, and is between 30 and 40% more expensive than in the US. Our total budget for equipment acquisition in two years was 75,000 USD, which is only a fraction of our direct competitors' investments.

With regard to the antispam service, it became necessary to develop a product that could compete with the systems offered by the big ones. Given the hostile conditions imposed by the existence of spam (dictionary attacks, spams with high degree of obfuscation and refinement, phishing, trojans, mail-bombs, etc.) it becomes very difficult to achieve an excellent uptime while repelling attacks. One must also be careful that the user does not lose mails because of false positives in the classification strategy, that he does not become flooded with spam or spam notifications, and dangerous mails do not make it through to his mailbox. In addition, the technical infrastructure for spam classification should not introduce noticeable delays in the delivery of mails. Finally, the mail system has to be protected from spammers who might misuse it to send spam.

The opensource paradigm tends to require hiring large teams of system administrators, operators and programmers who apply patches, correct bugs and integrate platforms. The opposed paradigm is also costly because of expensive software licences, the need for increasingly expensive hardware and a large support staff. So the challenge was to find the right mixture for scarce human and monetary resources, high stability and predictability, and quick and reliable deployment. In Buenos Aires, well-trained Computer Science professionals are hard to find, most of them live and work abroad, while the remaining have stable jobs either at the government or big companies.

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