Bayside Networks National Provider of Trusted and Experienced IT Services

Are you using Postini as a smart-host with your Exchange system? Are you having problems with delayed outbound mail?

There are certain problems associated with sending mail out through Postini with Exchange 2003 – this presentation describes many of those issues.

Our consultant, David, developed this Powerpoint presentation to help explain the differences between each method:
Comparison of Outbound E-mail Delivery Strategies (.ppt).

There are distinct pros and cons associated with each of the three methods! We used this presentation to help one of our valued clients better understand their options for sending mail out of their systems.

Direct Delivery Characteristics

Advantages to the originating mail server administrator

• High degree of visibility into the email delivery process
• No additional components or outside services needed
• Simple, minimal, configuration minimizes points of failure

Disadvantages to the originating mail server administrator

• Server and IP address are directly visible on Internet
• Server administrator needs to handle resolution of blacklist issues
• Administrator needs to perform monitoring and troubleshooting
• Mail delivery may be affected by connectivity of mail server
• Server needs to be able to handle size of queues and retries

Smart Host Characteristics

Advantages to the originating mail server administrator

• The originating server does not need to perform queue management
• Monitoring is simplified, server becomes almost “maintenance free”
• Originating server is isolated from the Internet; remains anonymous
• Delivery troubleshooting is handled by the Smart Host administrator
• Resolution of blacklisting is handled by the Smart Host administrator
• Outgoing bandwidth reduced for multiple-recipient messages

Disadvantages to the originating mail server administrator

• Loss of visibility into the delivery process; can’t status messages
• Smart Host is a potential additional point of failure in delivery
• Traffic from other Smart Host users could increase blacklist risk

Postini SMTP Relay Characteristics

Advantages to the originating mail server administrator

• Originating server is isolated from the Internet; remains anonymous
• Resolution of blacklisting is handled by Postini service
• Outgoing mail is scanned for viruses

Disadvantages to the originating mail server administrator

• Administrator needs to perform monitoring and troubleshooting
• Interjection of Postini in mail path complicates troubleshooting
• Exchange cannot manage the queue optimally with Postini
• Server needs to be able to handle size of queues and retries
• Postini service is a potential additional point of failure in delivery
• Traffic from other Postini users could increase blacklist risk

Comparison Between Methods

Exchange SMTP queues

• Postini: One queue for all messages, problem deliveries mixed in
• Direct: One queue per destination, only problems will have a queue
• Smart Host: One queue for all messages, queue will remain empty

Content filtering

• Postini: Service provides content scanning of outgoing mail
• Direct: Any scanning would be performed on originating server
• Smart Host: Service might or might not provide scanning of mail

Visibility of servers

• Postini: Mail appears to come from Postini addresses
• Direct: Mail would show IP address of originating server
• Smart Host: Mail appears to come from the Smart Host

Delivery performance

• Postini: Problem destinations might affect delivery of other messages due to shared link state and intermingling of messages in queues
• Direct: Problem destinations will only affect those destinations since each message is maintained in a separate queue
• Smart Host: Messages leave server immediately and queue stays empty, Smart Host manages delivery of messages and retries

Monitoring and troubleshooting

• Postini: Server administrator performs delivery troubleshooting, having Postini as an intermediary complicates diagnosis
• Direct: Easy to monitor for issues, server administrator needs to perform all troubleshooting of deliveries
• Smarthost: Very little that administrator can do, Smart Host performs all monitoring and troubleshooting

Aside from Postini’s own documentation – there isn’t much information available online regarding Postini’s outbound relay methodology and the pros and cons it presents to their customers.

Feel free to call us, (858) 654-4080, for more details on this subject; or any other technical support needs you might have.

Chris