Configuring on-premises messaging servers to coexist with IBM SmartCloud iNotes

Introduction

Hosted mailing solutions have become quite popular, and many service providers are providing them successfully for businesses. SmartCloud iNotes is a hosted mail solution for businesses that provides email, calendar, and contacts management.

Many of these businesses are also opting for a combination of hosted and on-premises email solutions when they have a mix of online and on-premises users who access email, as defined below:
This model, in which organizations need to maintain on-premises email servers and hosted email servers together is called email coexistence. There are several challenges to be addressed in this model:

• Maintaining a common domain name for the email addresses spanning across on-premises server to hosted iNotes.

• Maintaining a common corporate directory for email address lookup between on-premises and hosted iNotes.

• Configuring mail routing between hosted iNotes and on-premises mail servers.

In this article we discuss how to resolve these questions so as to implement a coexistence model for an organization, whereby on-premises mail servers such as Lotus Domino and Microsoft Exchange can coexist with IBM’s SaaS SmartCloud iNotes mail service.

Approach

The approach we suggest here uses the smart host feature provided by mail servers like Lotus Domino or Microsoft Exchange. It's a common practice to use this feature to support a secondary server, in case the main server goes offline for maintenance.

MX Record points to the on-premises Lotus Domino or Microsoft Exchange smart host server. Mail for hosted users is routed to hosted iNotes, whereas mail for on-premises users is delivered to their mail boxes.

We explain the approach with the help of a real-time example, using a fictitious domain name for an organization. We then specify step-by-step instructions to enable smart hosting on Lotus Domino and Microsoft Exchange servers.

Let' take an organization with a domain name corporate.com that has mail users on their on-premises server and hosted mail server iNotes. The on-premises mail server is configured as the “Primary Server” through the MX Record configuration for the “corporate.com” domain, for example, users@corporate.com.

Configuring the on-premises server as the primary mail server implies that all mail for the corporate.com domain will be sent to this server first. The mail server would then route the mail to users on iNotes, if they do not exist on the primary server, which is done via the smart host configuration we describe later in this article.

Environment setup

Our environment is set up as follows:

• The company domain is corporate.com.

• The on-premises mail server exists on the host “mycompany.corporate.com” (assuming a standalone server installation for simplicity).

• The domain name for corporate.com has an MX record in DNS pointing to the host myserver.corporate.com.

• The host name has an “A” record in DNS to identify the domino.corporate.com with its IP address.

• SmartCloud iNotes creates the same corporate.com domain and provisions user accounts on iNotes.

• The on-premises directory is the master, and iNotes replicates the changes from the on-premises master directory.

• The Primary mail server is configured as a smart host to forward all the mail for users whose email address is corporate.com but whose mail file does not exist on a mail server.

User configurations

Let's assume the users for the organization are set up as follows:

• dUser1 (dUser1@corporate.com) and dUser2 (dUser2@corporate.com) are set up on the on-premises server.

• iUser1 (iUser1@corporate.com) and iUser2 (iUser2@corporate.com) are set up on the hosted iNotes server.

• The on-premises user directory has the entries for all the users of the organization, and this is replicated to the iNotes directory. This ensures the address lookup is consistent on both on-premises and iNotes.

Mail routing scenarios

There are many possible scenarios of mail going between on-premises and SmartCloud iNotes mail servers, and we discuss all of them the subsections below.

All the scenarios can be divided into two broad categories, namely:

• Inbound mail routing in the coexistence model, as shown in figure 1
• Outbound mail routing in the coexistence model, as shown in figure 2

Figure 1. Inbound mail routing



Figure 2. Outbound mail routing

Let's now discuss these scenarios in more detail.

Mail from on-premises user to iNotes user
In this scenario, dUser1@corporate.com sends an email to iUser1@corporate.com:

1. The email is routed to the mail server pointed to by the MX record for the corporate.com domain, which is the on-premises server mycomany.corporate.com.
2. The on-premises server looks up the directory for the user and finds a Person record for iUser1@corporate.com but does not find the mail file.
3. Since the Person record exists for the user, smart host routes the email to the iNotes SMTP server, and the email is delivered.

Mail from external user to iNotes user
In this scenario, someuser@otherdomain.com sends an email to iUser1@corporate.com:

1. The email is routed to the mail server pointed to by the MX record for the corporate.com domain, which is the on-premises server mycompany.corporate.com.
2. The on-premises server looks up the directory for the user and finds a Person record for iUser1@corporate.com but does not find the mail file.
3. Since the Person record exists for the user, smart host routes the email to the iNotes SMTP server, and the email is delivered.

Mail from one iNotes user to another iNotes user
Here, iUser1@corporate.com sends an email to iUser2@corporate.com, and the inbound mail servers are different from the outbound mail servers in iNotes:

1. The outbound mail server will look for the MX record for the corporate.com domain and deliver the mail to the on-premises Domino server, domino.corporate.com.
2. The on-premises server looks up the directory for the user and finds a Person record for iUser2@corporate.com but does not find the mail file.
3. Since the Person record exists for the user, smart host routes the email to the iNotes SMTP server, and the email is delivered.

Mail from an iNotes user to a Domino user
Here, iUser1@corporate.com sends an email to dUser1@corporate.com, and the outbound mail servers for iNotes are separate and distinct from inbound mail servers:

1. The outbound mail server looks for the MX record for the corporate.com domain, which is the on-premises server, domino.corporate.com, and delivers the email.
2. The on-premises server looks up in the directory for the user and finds a Person record for dUser1@corporate.com.
3. The Domino server finds the mail file for user dUser1@corporate.com and accepts the email.

Mail from an external user to a Domino user
Here, someuser@otherdomain.com sends an email to dUser1@corporate.com:

1. The email is routed to the mail server pointed to by the MX record for the corporate.com domain, which is the on-premises Domino server.
2. The on-premises server looks up in the directory for the user and finds a Person record for dUser1@corporate.com.
3. The on-premises server finds the mail file for user dUser1@corporate.com and accepts the email.

Mail from one on-premises user to another on-premises user
Here, dUser1@corporate.com sends an email to dUser2@corporate.com:

1. The mail server for the corporate.com domain is the same server; hence, the mail server will look for dUser2@corporate.com and, since the user exists locally, it will deliver the mail to dUser2@corporate.com's mail file.

Mail from an on-premises user to an iNotes user
Here, dUser1@corporate.com sends an email to iUser1@corporate.com:

1. The mail server for the corporate.com domain is the same server; hence, the server will look for iUser1@corporate.com.
2. A Person record exists for iUser1@corporate.com; however, the mail file does not exist so Domino smart host will route the email to the iNotes server.

Invalid mail address
In this scenario a mail is sent to a user, say, nonexistent@corporate.com, who does not exist on either the on-premises or iNotes server:

1. The email is routed to the mail server pointed to by the MX record for the corporate.com domain, which is the on-premises Domino server, domino.corporate.com.
2. The on-premises server looks up the Person record for the user, nonexistent@corporate.com, but does not find it.
3. The server discards the email and sends back an invalid-address message.

Advantages and disadvantages of this approach

In the approach discussed above, all the mail is routed via the on-premises SMTP server, which has some advantages and disadvantages:

Advantages
Corporate guidelines can be enforced on the on-premises mail server, such as the message size cannot exceed 25 MB.
Spam and anti-virus rules for the corporation can be uniformly applied for on-premises mail and for hosted mail.
Archival policies can be applied for all the mail, on-premises and hosted.

Disadvantages
When mail is sent from one iNotes user to another, the mail must do a round trip, to and from the hosted mail server.
The on-premises Domino SMTP server must be sized to handle the mail traffic for both on-premises and hosted user populations.

Mail server configurations

This section provides step-by-step instructions to configure the smart host feature in the two most popular mail servers, Lotus Domino and Microsoft Exchange.

Configuring smart host on Lotus Domino

First, verify the Domino settings and SMTP on Domino:

1. Open the Admin Client for Lotus Domino.
2. Select and open the Current Server document from the Configuration tab.
3. Click the Basics tab and edit the Server document to point to the proper domain names, ensuring that the SMTP listener task is enabled (see figure 3).

Figure 3. Basics tab of Current Server document



Second, enable the SMTP and configure smart host:

1. Select “Configurations” under Messaging in the left-hand navigation pane.
2. Select and open the Server document, and select the Router/SMTP, Basics tabs (see figure 4).
3. Ensure that the “SMTP used when sending...” field is set to Enabled.
4. Enable the smart host option, and enter the SmartCloud iNotes server address.
5. Save and close the document.

Figure 4. Configuration Settings' Router/SMTP, Basics tab


The Domino server is now configured to route mail to SmartCloud iNotes.

Configure Lotus Domino to accept mail for the corporate.com domain
To do this, create a Global Domain document as shown in figure 5. This enables Lotus Domino to receive mail from multiple Internet domains and determines how the Domino server sends and receives mail from external domains. Save and close the document.

Figure 5. Global Domain document


Setting up the network to receive mail
To do this, ensure that:

1. The MX record and A record for corporate.com is pointing to the Domino instance.
2. The machine is ping-able from the Internet and SMTP listener is working by doing a telnet to the Domino server on port 25.

Creating Person records for iNotes users

1. Open the Domino Directory, and in the People view, and create a new Person document by clicking the Add Person button.
2. Update the user details for the record, as shown in figure 6.
3. Choose “Other Internet mail” from the selection in the Mail system field.
4. Enter the user's Internet address, to facilitate user account lookup.
5. Save and close the user document.
6. Repeat these steps for all SmartCloud iNotes users.

Figure 6. iNotesUser1 Person document

Configuring smart host on Microsoft Exchange 2007

To do this, first verify the Exchange settings and SMTP on Exchange:

1. Open the Exchange Management Console, and expand Organization Configuration.
2. Select Hub Transport, and click the Send Connectors tab (see figure 7).

Figure 7. Exchange Management Console window



3. In the CorporateCom Properties window, select the Network tab (see figure 8).
4. Select the option, “Route mail to the following smart host,” to add a smart host to SmartCloud iNotes.
5. Click the “Add” icon to add the smart host address for SmartCloud iNotes.
6. Enable (checkmark) the option, “Use External DNS Lookup settings on the transport server,” for the resolution of the name server to IP address.
7. Click OK to save the settings.

Figure 8. Network tab



8. Click the option for adding a smart host to SmartCloud iNotes, and enter the SmartCloud iNotes server address, as shown in figure 9.

Figure 9. Add smart host address


Configuring accepted domains
Accepted domains are configured as global settings for the Microsoft Exchange organization and on computers that have the Edge Transport server role installed. There are three types of accepted domains: Authoritative, Internal Relay, and External Relay (see figure 10). Select the Internal Relay Domain option.

Figure 10. Internal Relay Domain option


The Exchange 2007 server is now configured to route mail to SmartCloud iNotes.

Conclusion

The article described the scenario in which a business opts for its on-premises messaging servers, like Lotus Domino or MS Exchange, to coexist with SmartCloud iNotes. The co-existence model is implemented so that both SmartCloud iNotes users and on-premises users can share the same domain name for their email addresses.

Our approach requires the addition of an MX record to point to the on-premises SMTP server for the given domain name that is being shared, and it uses the smart host feature supported by Lotus Domino or MS Exchange that routes incoming mail to an on-premises user's mail box or forwards it to SmartCloud iNotes, if the user exists in iNotes.

Resources

• developerWorks® Lotus article, “Introducing IBM LotusLive”.
• SmartCloud wiki article, “Getting Started Guide for LotusLive iNotes Administrators.”
• developerWorks product page, “Lotus iNotes - Web based email software.”
• IBM Lotus Notes/Domino 8.5 Forum

About the authors

Anurag Srivastava has roughly 15 years of IT experience, working for many different clients in many different countries, including the US, the UK, and India. He has been with IBM Software Labs since 2007 where he works in the social and collaboration domains for the CIO group. He is currently the Team Lead for BSS Partner Integration for IBM's Cloud offering . He has filed two patents, published many articles, and also speaks at seminars on SmartCloud for Social Business, Mashup, and IBM WebSphere Portal. You can reach him at anuragsr@in.ibm.com.

Sujit Shet has been with IBM India Software Labs since July 2007 and is part of SmartCloud for Social Business Integration development team focusing on integration of various products and services in SmartCloud for Social Business for customers. His research and development includes Mail & Data Migration Assets for SmartCloud iNotes. You can reach him at sujishet@in.ibm.com.

RajKiran Guru has been with IBM since 1999 and has led and architected several customer integrations. He also serves as a Technical Evangelist, enabling partners, customers, and IBMers on LotusLive capabilities. He has published several articles for developerWorks and external publications, and has co-authored two IBM Redbooks publications. You can reach him at Rajkirang@in.ibm.com.