Axigen GrowSecure™

The Axigen Solution: Overview & Architecture

Axigen GrowSecure™ secures reception, transit and delivery of email. Messages can be filtered at the server, domain, or user level via a variety of filters, including anti-virus / anti-spam (any third party solution), anti-spoofing, Domain Keys and custom SIEVE scripts.

The Axigen mail server offers high-end features for large scale implementations by providing speed, security, reliability and a failsafe storage system helping you to avoid any interruption of service or loss of data.

Scalability

  • Stateful services

Non-distributed email solutions, where account information (configuration and messages) is stored on a single machine, allow vertical scalability through hardware upgrades (CPU, RAM, disk). However, due to limitations in a typical machine (i.e. max 2 CPU, max 4 GB RAM etc.) an upper limit is eventually reached, where one can no longer upgrade one machine – vertical scalability limit.

When the vertical scalability limit is reached, the only solution available is to distribute account information (configuration and mailbox) on more than one machine – horizontal scalability. Since information for one account is atomic and cannot be spread across multiple machines, the solution is to distribute accounts on more than one machine. This way, for a single account, there will be one machine responding to requests (IMAP, POP, SMTP, WebMail) for that specific account. Thus, when the overall capacity (in terms of active accounts) of the messaging solution is reached, adding one more machine to the solution and making sure new accounts are created provides a capacity upgrade, therefore allowing virtually unlimited horizontal scalability.

  • Stateless services

Since stateless services do not store information over multiple sessions, we can assume that two different machines are able to service requests for the same account. This way, horizontal scalability can be achieved by simply adding more machines providing the same service in the exact same configuration. The only remaining requirement is to ensure that requests to a specific service are distributed evenly throughout the machines providing that specific service (i.e. if the system contains two machines providing IMAP proxy services, half of the incoming IMAP connections must reach one of the machines and the rest of the connections must reach the other machine). This functionality is provided by a load balancer.