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Mail Security

This page is devoted to mail security and anti-spamming behaviour.

Our Mail Servers

We implement a number of features in our email servers to minimise hacking, secure your mail, provide a level of anti-spamming and to mimimise our own risk of being used as a spam relay (a so called open relay).

Mail Relay

We relay mail only for our own logged in (authenticated) customers and for customers in the domains that we handle. This means that we cannot be used by an external third party to relay spam.

First and most important, this makes it more difficult for spammers and others to send mail by limiting the sources available. Second, if we did NOT we could (quite rightly) be blacklisted by the anti-spam movement. So all your mail could get rejected. Finally it limits theft of our bandwidth which means there is more for you, not unscrupulous third parties.

We regularly check our relays to make sure they have not been accidentally opened.

Mail Protocol Checks

Our mail server is configured to validate the 'Return-Path:' address on incoming mail. If it does not exist the mail item is rejected. We do not accept mail to an address in your domain that does not exist (some mailers dump it into a default mail box). Finally we do not accept mail if both the 'to' and 'cc' fields are blank - again it is rejected.


We do NOT use a blacklisting service. We have had too many problems with incorrectly blocked mail due to poor blacklisting services. Here we consider the cure worse than the disease.

Anti-Spam Filtering

We do NOT use mail server spam filtering (though our mail server software provides a rich set of features for this function).

We are NOT OPPOSED to implementing such a feature - it's just very difficult to define across a large customer base what is, and what is not, spam. One person's spam may be another person's information.

We do optionally provide a service called greylisting which we believe is the best current technological approach to reducing spam loads and has the added benefit of an almost zero possibility of false postives - unlike clasic spam-filtering techniques.

Finally we have implemented SPF records on all our domains since 2004 since again we believe this initiative is a useful anti-identity theft measure especially when used in conjunction with greylisting.

Want to know more

Check the sidebar links for sources to help you verify mail headers and other exotica and our email FAQs pages for more information and email agent configuration.

We encourage you to notify us at mailabuse at zytrax if you consider you are having serious problems with spam (click the 'forward' button on your mailer). We also urge you to implement your own spam filtering rules using your email client software (e.g. Netscape mail or Outlook Express) since these policies are under your control and can be tailored to your organisational or personal needs.

Problems, comments, suggestions, corrections (including broken links) or something to add? Please take the time from a busy life to 'mail us' (at top of screen), the webmaster (below) or info-support at zytrax. You will have a warm inner glow for the rest of the day.


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