Using and administering electronic mail

Comparison of sendmail with MMDF

Both of these MTAs:

provide a general inter-network mail routing facility with automatic routing to network gateways, message batching, queueing, and retransmission.
support either Internet-style addressing (user@domain) or UUCP-style addressing (host!user).
work with delivery agents such as SMTP (Simple Mail Transfer Protocol), X.400, and UUCP.
provide aliasing and forwarding capability.
support customized mailers.
provide flexible configuration.
support routing of messages that conform to the Multipurpose Internet Mail Extensions (MIME) standard.

MMDF supports two-stage timeout, which sendmail does not support. MMDF uses two-stage timeout when routing mail through machines to users. If a message cannot be forwarded to a particular machine or to a particular user on a machine, a warning is sent back to the mail message sender. This is stage one. At some future time (configurable by the administrator), the message is relayed again. If it fails, a failure message is returned to the sender, and MMDF makes no further attempts to resend the original message. This is stage two.
MMDF offers several substantial benefits over sendmail, including:

Graphical utilities for configuration and administration.
Configuration files that are easy to read and understand.
The ability for end-users to configure their own sorting parameters.
A larger set of supported delivery agents.

Because MMDF does not consider backwards compatibility a design goal, the address parsing is simpler but much less flexible.

It is somewhat more difficult to integrate a new delivery agent (``channel'') into MMDF. In particular, MMDF must know the location and format of host tables for all channels, and each channel must speak a special protocol. This allows MMDF to do additional verification (such as verifying host names) at submission time.

MMDF strictly separates the submission and delivery phases. sendmail understands each of these stages, but they are integrated into one program.

sendmail is difficult to configure manually. This implementation of sendmail, however, includes a script that creates a basic configuration that is adequate for most sites.