Email has become the de facto method of communication in business and Ilisys customers have grown to expect their email to be handled securely, promptly and reliably.


Delivering on this expectation is complex, as email typically passes through many systems from sender to recipient and each system presents the opportunity for error or failure.


Unlike many providers, Ilisys has developed systems to ensure that your email is managed as carefully as is technically possible while within our network. In addition, advanced learning systems prevent the delivery of spam and email viruses.


Design challenges

• Email transit times are to be kept to an absolute minimum;

• Services are to be available 24x7 with uninterrupted uptime;

• Email spam and viruses blocked as completely as possible;

• Over-engineering, to allow for spam and virus storms.


Attributes of the Ilisys email system

• Splits the email services into logical functions:

   - Incoming email;

   - Spam/virus scanning;

   - Delivery to local accounts or forwarding to remote email addresses

   - POP/IMAP;

   - Webmail.

• Clusters each service for maximum reliability (except webmail)

• Uses best of breed, open source software for each function

   - qmail for smtp, queue management, storage and forwarding;

   - amavisd-new, ClamAV & SpamAssassin for virus & spam scanning;

   - Courier IMAP for POP and IMAP servers;

   - SquirrelMail for webmail.


• Blocks connections from known spammers using Spamhaus.


• 24x7 monitoring of queue levels and service availability for fast response if problems arise.


How it works

When someone sends an email from the mail client on their computer, typically it gets sent to their ISPs outgoing mail server (aka SMTP server). That server will queue the email for ongoing delivery to to the recipient's mail server.



If Ilisys manages that email for the recipient, it will be received on one of our cluster of MX (or Mail eXchange) servers. In order to minimise spam, these servers will not accept connections from certain computers run by known spammers as listed at Spamhaus.org.


From there, we pass the email to our spam/virus scanning cluster. If the email contains a virus detected by the ClamAV anti-virus scanner, it will be quarantined at this point. The email is also processed on these servers by SpamAssassin. This software gives each email a score as to the likelihood of it being spam. If that score is over 8, then it is virtually certain to be spam and will be quarantined as such. If that score is over 5, it is quite likely to be spam and will be marked as spam in the headers and, if the recipient has requested it, in the Subject line. If that score is less than 5, it is probably not spam.


As this is only a probability, and since spam is always changing, some email that is spam may not get marked as spam. However, we set these levels so that we are very unlikely to get any false positives, that is email quarantined that is legitimate email.


After our email is cleared of being spam or a virus, it gets passed to our delivery mail servers. These look at the settings for the recipient email address as set in the Ilisys Toolkit and either delivers to a local mail account, or forwards to an external email address as appropriate.


For email delivered to a local mail account, this will be placed in the user's mail directory on our central NetApp filer to await collection by the recipient using either a mail client on their computer, or Ilisys' webmail.


Users using a remote mail client can use either POP or IMAP protocols to collect the emails via our cluster of POP/IMAP servers. Alternatively they can access their emails online via our webmail server.