Global System Services Corporation (GSS) - The leading provider of email and messaging, directory services, and groupware consulting and professional services

> Support > Domino SMTP MTAs

7.4.2

Do I Need Multiple Domino SMTP MTAs?

(Published in DominoPower Magazine, October 1998)

Do I Need Multiple Domino SMTP MTAs?

Every day, we get mail from our readers. Occasionally, there is a letter we think would be better served in a monthly letters to the editor column. Normally, our editorial staff is not really equipped to answer questions better served by your favorite Domino consultant. But Senior Technical Editor Ron Herardian, an independent consultant and messaging expert, volunteered to help out. This month: How to configure multiple SMTP MTAs and use multiple DNS domains.

Setting up SMTP email without transiting via the hub server

My office is the largest office in a worldwide Lotus Notes domain and I want to set up my Notes server so we can send and receive SMTP email without going through our hub server in Belgium.

We are running version 4.5.4 of the Domino server and I have downloaded the MTA (Message Transfer Agent), but the overall Notes administrator in Belgium is saying that it's impossible to set MTA to work up on another server in the domain.

To start with, all I want to do is to set up the MTA so all non-Notes addressed emails (except faxes) go straight to the Internet as opposed to going in a rather circular route of:

London -> Internet -> Belgium -> Internet -> Recipient

Is this possible? If so, how can we do it?

Andy Owen (aowen@amrop.co.uk)
IT Manager, Whitehead Mann Group

Ron Herardian Responds:

Multiple SMTP MTAs (that's Simple Message Transport Protocol Message Transfer Agents) can be implemented within a single Notes network, each running on a separate server. Based on my experience with Domino messaging customers, this is a common issue in large Domino messaging systems. However, before you implement additional MTAs there are several things to consider.

Conceptually, the fact that you route Notes mail between Domino servers, over the Internet, to and from the SMTP MTA is not relevant to the overall message routing topology -- unless there are capacity problems resulting in routing delays or high communications costs that would justify additional MTAs. A related issue is whether or not you have established a capacity planning framework for Domino messaging.

It is indeed possible to distribute multiple SMTP MTAs to different locations. It is also possible to use multiple DNS domains to route inbound SMTP messages to different sites around the world. Alternatively, an intelligent mail hub can route inbound Internet mail, based on the user ID, to different MTAs (or to various MTAs and gateways). This can be done using sendmail with custom rewriting rules (I recommend Sun's implementation on the SPARC platform) or by an
LDAP-enabled implementation of SMTP such as Netscape Messaging Server, which can be synchronized with the Domino Name and Address Book using third party directory synchronization products such as WorldTalk and my
own company's GSS LDAP Synchronizer.

Before discussing architectural changes to your mail routing topology and SMTP MTA system design, we should examine what motivates you to look for a solution. Mail routing delays, for example, are typically either configuration issues or capacity problems relating to either network or server capacity.

Mail routing delays are the most common issue but they are not caused by product limitations. Mail routing configuration and inefficient mail routing can be corrected. Capacity issues can be addressed simply by upgrading servers or networks. Each customer facing this problem needs to compare the costs of installing, administering, supporting, and maintaining multiple Internet connections and SMTP MTAs with the costs of resolving configuration and capacity problems. I don't recommend taking any action until those specific problems you have noted are
clearly understood.

Capacity planning is always an issue where the ever rising volume of Internet email is concerned. The least effective methodology is to determine, based on the negative impact on users and your information systems department, that capacity problems exist. As the market and the products continue to mature, and as their focus on Internet messaging
technologies continues to sharpen, we'll have better tools for monitoring and data collection -- and these tools can be utilized for capacity planning.

The best way to make architectural decisions for Domino and Internet messaging (i.e., centralization versus distribution of SMTP MTAs) is to combine financial factors and capacity planning data. The methodology I use use for capacity planning is to collect and apply messaging statistics to create a mathematical model of the messaging environment.

The capacity model can be used to predict required network bandwidth and server capacities, as well as to project "what if?" scenarios for architectural design purposes. One of the main benefits of capacity planning, however, is the ability to predict when the capacity of networks or servers will be exceeded and to respond before users are
negatively impacted.

Ron

--