For those customers using Microsoft Exchange servers in-house, our Mailwall services are invaluable.
One of the main downfalls in the way MS Exchange works is the way it handles bounces – it attempts to respond to every fake address spam it receives with an email. This can cause extreme performance issues. By using the Computer Variations Mailwall service in front of the MS Exchange server, not only is the amount of unwelcome traffic received reduced tremendously, but also those performance issues are obviated.
Customers who have Exchange servers choose one of two levels of protection that we offer:
Mailwall 1. This is an extremely simple – zero maintenance – configuration in which our mail server becomes the listed (in the DNS) default mail host for the domain, and acts very much like a firewall for mail for the whole domain. First a global filtering is applied (rejects approximately 65% of incoming connections) then incoming messages are held in queue for just the time necessary to query your server to ask if it will accept for this particular user; if authorized by your server it is forwarded immediately. Should your server be down temporarily, messages are queued for 72 hours. Note that the Mailwall 1 configuration is non-tweakable, server defaults apply – naturally these are somewhat more permissive than a carefully configured system, see next option.
Mailwall 2. Individually maintained forwards. In this configuration our server is configured on a per mailbox basis by either your domain administrator or the individual users. Global defaults for the domain can be set as well as individual choices. All of them can override the second level spam weighting and filtering at the server (the first 65% of rejects still apply). Logs are available to users of the results of their choices for additional fine-tuning. Global reports for the domain are available to the administrator. Queuing to allow for temporarily unavailable servers is just as for the Mailwall 1. This second option is much more powerful – and of course requires some more administration.
With either option, it is recommended that the MS Exchange server be configured to accept mail only from our server – this can be done in the network firewall for example – this will provide a significant additional level of security. Outgoing mail can optionally be sent through our mail server also (recommended). An SPF record is strongly advised to further optimize the spam weighting process.
Mailwall 1 is billed at $25/month, flat rate. Optionally, virus scanning – with definitions updated on an hourly basis 24/7 – is an additional $25 per month, flat rate.
Mailwall 2 is billed at $25 per 25 users per month. Optionally, virus scanning – with definitions updated on an hourly basis 24/7 – is an additional $25 per 25 per month.