~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
From: "Eric Levine" <[EMAIL PROTECTED]>
Subject: CDONTS vs ASPEMail


: Quick question...  I have been using CDONTS to handle all of our
: ASP-driven e-mail requirements (Classic ASP/IIS5/Win200).  Does anyone
: have any pros/cons to going this route?  Is using a third-party
: component like ASPEmail worth the extra $$$?

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That depends on your requirements. CDONTS requires that you have the MS SMTP
server installed on your webserver. This may/may not be acceptable to you.
(for example the firm may have its own SMTP server located on a separate
machine, or may not be using the MS SMTP server). ASPEmail or JMail or
whatever can use either TCP sockets to communicate with a server, or can
drop mail into the MS SMTP server's "pickup" folder.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
: To date, using CDONTS has been fine.  One thing I don't like however,
: and it may be this way for all third party components as far as I know,
: is that once the email is sent you do not know if there was a failure on
: delivery.  Does anyone know of a link that discusses how to poll the
: SMTP server to see if any mail had a delivery failure?

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You need to look into the SMTP specification to get the gory details.
Delivery failures can be caused by lots of different things.

a) The remote domain does not exist. A sockets based component that attempts
to connect to the remote domain's mailserver by using DNS will tell you that
there is an error.

b) The remote domain does exist, but does not have an MX record, and the
first A record does not respond. Again, this is real-time, and so a sockets
based component will tell you that it was unable to connect to the remote
server

c) The remote server returns some other error code, eg user does not exist,
user mailbox is full etc. If the sockets component it connecting directly to
the remote mailserver you'll get an error.

d) None of the above will be registered by the component if your component
connects to your organisation's mailserver (which then, in turn, attempts to
connect to the remote mailserver). Instead, an NDR report is generated to
the From: address specified in the email. This is the usual error handling
method with SMTP. Why would you connect to your own local SMTP server
instead of a remote SMTP server directly? Performance.

e) The beauty, and strength, of email is that it is a store-and-forward
technology that allows for transient routing problems. This means that there
are few cases where a component can return an error to you, since these
errors need to be detected in real time. Instead, SMTP relies on email
non-delivery-reports (NDR) to inform users of problems.

f) If you need an automated way of handling email delivery problems, use
dedicated list server software (eg Lyris, or LSoft's Listserv). These will
handle bounced emails etc, removing people from lists, or altering their
status depending on what rules you put in place. As an added benefit, these
also store their data in ODBC compliant database (Lyris uses SQL Server from
memory), so it makes it easy to integrate into whatever websites/systems you
already have.

Cheers
Ken


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