What are the benefits
of Enhanced SMTP?
Question Background:
SMTP stands for "Simple Mail Transport Protocol"
SMTP is the name of the protocol that is used to transfer email messages between
computers. This "language" has only ten or so words and some additional
enhancements (called Enhanced SMTP or ESMTP) to reduce bandwidth and improve
performance.
Answer:
Below are ESMTP commands supported by GMS Mail:
8BitMIME: The sender uses this command to announce that is supports higher bit
ASCII transmission.
AUTH: Use 'Auth' to set up authenticated SMTP transactions. GMS Mail supports
three types of authentication. (LOGON, MD5, CRAM-MD5)
DSN: This option asks the Gordano mail server to confirm that a transaction
was completed as desired. You could you use DSN to act as a receipt mail message
to confirm when the intended receiver has received your message.
ENHANCED STATUS CODES: This gives precise error codes relating to the status
of delivering mail. These are only delivered to servers who issue the EHLO command
to indicate that they understand ESMTP, all other servers receive the standard
responses codes. Example: If mail failed to send, using standard SMTP the server
might issue a '550 delivery failure' whilst using enhanced SMTP the server might
return 550 5.4.3 delivery failure. The extra numbers indicating that this was
definitely because of a routing server failure.
ETRN: This command is also known as QSND. It is specifically designed to allow
intergration with dial-up mail servers. A dial-up mail server can connect to
GMS Mail and issue the ETRN command to basically force all the e-mail for its
server to be posted out. Note: The standard ETRN specified in RFC 821 is not
secure! Anyone issuing ETRN for a domain can retrieve mail for that domain.
GMS Mail can be password secured.
PIPELINING: A sending server can use pipelining to send all messages to the
receiving, at once using one connection without having to use the RSET command
each time.
RESTART: Also known as Checkpoint. If a connection is dropped half way through
a mail message, on its reconnection the Restart command from the sender gives
receiver the option of continuing.
SIZE: This can set restriction on the total size of messages accepted for a
particular domain. The sending server will state it has a message size constraint
to the receiving sender. This will then either be accepted or not.
VRFY: This command will actually verify a user. This enables external servers
to check that an e-mail account actually exists on your server. The response
will be the user specified with the domain name.
XTND: This command supports two elements; XMIT and XLIST
XMIT: This is used to send mail via POP servers rather than SMTP.
XLIST: This is used to list message headers.
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What are ESMTP and SMTP?
Answer:
SMTP is the name given to the protocol (or langauge) that is used to transfer
email messages between computers. The language has only ten or so words to reduce
bandwidth and improve performance. SMTP stands for "Simple Mail Transport
Protocol".
ESMTP, which stands for "Enhanced Simple Mail Transport Protocol"
adds many enhancements to the SMTP protocol. These include security, authentication
and other devices designed to save bandwidth and protect servers.
GMS supports a large number of Enhanced SMTP options
What is SMTP?
Answer:
SMTP is the name given to the protocol (or langauge) that is used to transfer
email messages between computers. The language has only ten or so words and
some additional enhancements (called Enhanced SMTP or ESMTP) to reduce bandwidth
and improve performance.
SMTP stands for "Simple Mail Transport Protocol". A conversation between
two computers using SMTP might look something like:
Who SMTP English
Computer 1 connect Call computer 2.
Computer 2 220 Greetings.
Computer 1 HELO Hello, how are you?
Computer 2 220 I'm OK thanks. What would you
like to do?
Computer 1 MAIL I'd like to send some mail from X
Computer 2 220 Looks fine to me.
Computer 1 RCPT The message is going to Y.
Computer 2 220 Ok, I'll except the mail from you.
Computer 1 DATA I'll send the message itself then...
Computer 2 342 Great, send it and let me know
when you have finnished.
Computer 1 message This is the message.
Computer 2 220 Excellent. I'll deliver it for you.
Computer 1 QUIT Goodbye.
Computer 2 220 See you again some other time.
As you can see, the protocol is very simple and allows messages to be transfered
very simply. There are several points you should notice:
There is no authentication or verification of who is sending the message. Gordano
sell a product call GMS Anti-spam which can add this feature.
The message itself is not checked to ensure that it is valid. This means that
messages can be "spoofed" or appear to be from someone other than
the real sender.
Enhanced SMTP (ESMTP) adds lots of additional features that are required to
reduce bandwidth, reduce latency and enhance error recovery. ESMTP connections
are initiated by replacing HELO in the example above with EHLO, the links below
show the advanced options available with ESMTP. All GMS products support these
options.