ETRN & ATRN Overview

ETRN is a network service that provides additional fail-over for your email system. Because it functions off-site it can capture mail in case of network outages and because it is distributed through 5 data centers it can route your mail even in the case of a major provider going offline. The service queues the email destined for your domain on our servers until your Exchange server comes online, which makes it particularly useful for people who have part-time or unreliable Internet connections (DSL, Cable, single T1's)

ATRN is also a network service that provides additional fail-over for your email system but is intended for hosts that do not have a static IP address (which ETRN requires). In ATRN/ODMR scenario, mail is delivered to the ATRN server where it is queued. The destination mail server then connects to the ATRN server and requests the queue by authenticating itself. The SMTP roles reverse and the client becomes a server in the same session - making it possible to implement through complex firewalls and without a static IP address.

• Holds your mail for 7 days in case of network or Exchange server outage.
  
• Flexible queue system allows you to request mail when you are ready to accept it or have our servers automatically check for availability.
• ETRN is housed at multiple data centers and uses intelligent routing to get around any big provider outages.
• Optional spam filtering can reject connections from known spammers and reduce your bandwidth costs.
• No embarrassing notices are sent to the email senders informing them that your server is down.
• No email is ever dropped or undelivered (especially important for automatic form generators, mailing lists, etc)
• ATRN allows you to run a dedicated Exchange 2003 or other mail server on a DSL/Cable connection without a static IP
• ATRN can be configured to function through complex firewalls that block port 25 traffic.

How does it work?

ETRN servers are primarily implemented as secondary failover servers that accept mail if your server/network is down. The mail is stored on the ETRN server until your server/network come back online at which time mail is delivered either automatically or by sending an ETRN command to our servers.

If the network/server are available, the mail is sent directly to your mail server. However, if that network or server become unavailable, the mail will be bounced to the sender. This is where ETRN comes in play:

The remote mail server will attempt to deliver to your primary mail server but will time out because of the network/server outage. The remote mail server then looks up the DNS record for a list of alternate mail servers and delivers mail to our ETRN. The mail is queued for up to 7 days, constantly checking if your server/network are back online. If/when your server recovers, all the mail that is stored on the ETRN is sent directly to your mail server.

ATRN is implemented in a similar way, but because of the firewall and/or no static IP address, our ATRN server is published as the only mail server. Your Exchange then connects to us and downloads the email upon authentication.

Configuration

Our engineers will walk you through the configuration of your Exchange and network to assure maximum effectiveness of ETRN. All you will have to do is put additional mail exchanger (MX) records in the DNS of the domain you wish to provide fail-over for. This process takes just a few seconds to complete.

ETRN is currently used to fail-over Microsoft Exchange, Lotus Notes, Novell GroupWise, sendmail, postfix and qmail. Mail is handled in accordance to RFC standards which assure compliance with all mail server software.

ATRN is fully compatible with Microsoft Exchange 2003 which is currently the only commercially available product that supports it properly. Both Microsoft Exchange Server 2003 (Enterprise or Standard) and Microsoft Windows 2003 Small Business Server support the ATRN protocol.

Pricing

The pricing for the ETRN server varies by the bandwidth (number of users, amount of mail) that your mail server will be using. The service starts at $35/month for an average 30 people office and includes 7 days of storage in case of a network/server outage.

Upgrade to ExchangeDefender

ExchangeDefender provides a full fault-tollerant and redundant network infrastructure for assured email delivery and security. Pricing is comparable to that of ETRN and provides far more reliable implementation that your business needs.