This note describes some new work we are doing on Internet Messaging routing, to be released in September.
The core of M-Switch's directory based routing (for X.400 and Internet Messaging) is based on RFC 1801, which I designed for X.400 routing. This is a highly functional specification, with many benefits, including:
- Uses directory reads for core routing, so will work across a distributed directory and does not rely on search indexes to work fast.
- Routing tree model gives easy management of multi-hop routing.
- MTA to MTA routing, as well as local delivery
- Load balancing
- Flexible User/Mailbox mappings (many:1 + 1:many)
To achieve this flexibility, RFC 1801 will have at least two directory entries for each mailbox. This will usually be managed automatically, or by a tool such as EMMA which understands RFC 1801.
LASER is an internet draft, specifying an approach to final hop Internet email routing. It has not been standardized, but this approach and variants are used by a number of products. The essence of LASER is to search for the Internet email address attribute in a directory, to determine the recipient.
This simple model ties in with Isode's Directory Vision of "One Directory Entry - One Person - One Account", and with the directory configuration approach we are taking with M-Box. There are many Internet scenarios where the benefits of the single directory entry approach of LASER outweigh the functional capabilities of the RFC 1801 approch.
LASER is ideal for ISPs. Single entry per user gives straightforward integration with provisioning systems. In this situation, the ISP will have full control of the directory, and so Isode provides a number of optional extensions to the LASER core, that provide addtional configuration flexibility.
The second scenario where LASER is useful, is where M-Switch is deployed in a boundary configuration, for example to filter Spam. In this situation, information on end users will generally be held in one or more directory servers. Performing address checking at the boundary is highly desirable, as it cuts down on overall load, particularly that caused by spammers with bogus addresses. Where information on recipients is stored in one or more LDAP servers with an email address attribute (which may be a standard or non-standard attribute), M-Switch can use this information to perform address checking.
We'll provide more information as we get closer to releasing this functionality.