praktikantenblog

It is a huge problem for both sides: The companies trying to send information to customers and the recipients, trying to figure out wanted email from junk ordners.

It is  not the easiest thing to setup a mail server so that it avoids being in error marked positive as spam.

The popular german mailservice GMX has published a long list of tips, that administrators of foreign mailservers should follow.

The problem is: It's better to  be hard. There are two main principles:

a) blacklisting

b) intelligence

In a, there is a list of mailservers, that should not be trusted. Some companies provide these blacklists and they are used in most of our tools, embedded in Thunderbird or guarding in front of our freemail services.

In b, everything  is about  pattern recognition   such as hidden markov chains 

In  both cases, and usually they are combined, by error, be it a machine that decides wrongly or more often a user that clicks on 'junk' can influence decisions and create false positives.
And Mailservers could run by bad configuration into the trap. And you could use email adresses or domain names, containing words in spam keyword lists.

In the case you run a young business, this can really suck. You sent invites to people or even your visitors invite their friends - and the mail is going to junk.

There is one principle, that could help here, called whitelisting.  

A good whitelist is the opposite of a blacklist. If you are good, your name is on the list and you can send as much spam as you want.

I know two  projects, that aim to provide a commonly used email  whitelist:

Spamhaus Whitelist  and the larger DNSWL