How antispam works on Mail.UA

1. A little about the project itself

Mail.UA - Ukrainian web-based email service. For a long time, the project was under development and beta testing, but since the summer of 2010 registration for the service is free and, unlike other similar services, is very simple: you need to fill in only 3 fields.
It is clear that all the usual functionality of a web mail is available. Among the features of the service can be noted:

• Fast desktop-like web interface. Of course, you won’t surprise anyone with AJAX, but in the case of Mail.UA, the interface still deserves special mention.
• The ability to create an unlimited number of additional (temporary) email addresses to your main mailbox (more on this below).
• Anti-spam system based on the principle of "white list".

This article, in fact, is about the last feature, because it causes the greatest number of disputes and ambiguous assessments.

2. About spam filtering in general

Usually a certain special program is engaged in spam filtering, which among the many incoming letters tries to identify spam messages by matching the contents of the message to a certain set of filters.
However, there are two big problems inherent in all spam filtering systems:

1. Users still receive spam in their mailboxes and this, in general, is not so scary - you can’t come up with protection that works at 100%. It is much more unpleasant when a “false positive” occurs. Normal mail is defined as spam by the system.
2. Worst of all, the user does not know how this system works and, in most cases, cannot in any way affect its operation. More precisely, sometimes it can (the Spam / Not Spam buttons in Gmail), but not significantly.

The main problem, as it seems to us, is the outdated principle by which anti-spam systems work. Indeed, before (at the dawn of the development of the Internet), most of the letters were "normal", and a smaller part was spam. Now (actually, already long ago) the situation has changed to the opposite: most of the e-mail messages on the network are spam.
Therefore, the filtering should now take place according to a different principle: by default we consider any incoming email to be spam and try to find the conditions according to which it can be considered “not spam”. Those. spam filtering turns into “non-spam” filtering.

3. Antispam in Mail.UA

Actually, according to this principle, it was decided to build an antispam in Mail.UA.
The question is: under what conditions will we select “normal” letters? Considering the second problem, we decided to take the principle of the “white list” as the main condition, which is formulated very simply:
If the sender’s address is “familiar” to you (read: “is in the address book”), then the letter is not spam.
This approach has one indisputable advantage: now the user knows exactly what he needs to do to get the letter into his inbox. There are many drawbacks of such a system, but all of them are solved by introducing additional conditions and mechanisms that help “good” letters to get through the anti-spam filter. In this case, the main principle remains unchanged, i.e. this is kind of our constitution. Everything else is laws that cannot contradict it.

So, in addition to the whitelist principle, Mail.UA has the following mechanisms for combating spam, or rather, eliminating “non-spam”:

• To register on various forums, sites, etc. It is suggested to use temporary addresses. If your primary address is username@mail.ua , then the temporary addresses will be something@username.mail.ua . They can be made as many as you want. Emails arriving at such addresses are not filtered. If necessary, any temporary address can be closed at the reception or deleted.
  It is recommended to create a separate address for each new registration - this way you will know exactly who sold your data to spammers.
• All letters from "unfamiliar" senders fall into the Spam folder . However, a letter will be sent to the return address with a link (if the corresponding option is enabled in the settings). By following the link and passing the “Humanity” test (CAPTCHA), the sender can “push” his message from the Spam folder into the recipient's Inbox .
• Each user of the service receives a special personal page (business card) with the address username.mail.ua . On this page, by default, there is a feedback form with which you can contact the owner of the page (again through the CAPTCHA check).

The proposed work scheme may show some complexity, but practice shows that the effort spent on its development pays off handsomely: there is practically no spam (only those letters that someone “pushed” manually), and all messages from various services are neatly laid out by daddies and marked with the necessary tags.
And most importantly, what the user gets is full control over the operation of anti-spam mechanisms. Now only you decide which letters you want to receive and which ones not.
What happens with a different approach (when you trust a solution to a certain program), we all know perfectly well from the films Terminator or Matrix :-).
Generally (a little PR at the end), come in , try it yourself. As I said above, registration on the service is very simple and absolutely free.