[Checkins] SVN: zope.sendmail/trunk/README.txt Recreated README.txt removing everything except for overview.

[Alexander Heavner]

Log message for revision 72633:
  Recreated README.txt removing everything except for overview.
  

Changed:
  A   zope.sendmail/trunk/README.txt

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Added: zope.sendmail/trunk/README.txt
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--- zope.sendmail/trunk/README.txt	2007-02-15 20:44:27 UTC (rev 72632)
+++ zope.sendmail/trunk/README.txt	2007-02-15 20:50:22 UTC (rev 72633)
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+zope.sendmail Package Readme
+============================
+
+Overview
+--------
+
+A package for email sending from Zope 3 applications.
+Email sending from Zope 3 applications works as follows:
+
+A Zope 3 application locates a mail delivery utility (`IMailDelivery`) and
+feeds a message to it. It gets back a unique message ID so it can keep
+track of the message by subscribing to `IMailEvent` events.
+
+The utility registers with the transaction system to make sure the message
+is only sent when the transaction commits successfully.  (Among other
+things this avoids duplicate messages on `ConflictErrors`.)
+
+If the delivery utility is a `IQueuedMailDelivery`, it puts the message
+into a queue (a Maildir mailbox in the file system). A separate process or
+thread (`IMailQueueProcessor`) watches the queue and delivers messages
+asynchronously. Since the queue is located in the file system, it survives
+Zope restarts or crashes and the mail is not lost.  The queue processor can
+implement batching to keep the server load low.
+
+If the delivery utility is a `IDirectMailDelivery`, it delivers messages
+synchronously during the transaction commit.  This is not a very good idea,
+as it makes the user wait.  Note that transaction commits must not fail,
+but that is not a problem, because mail delivery problems dispatch an event
+instead of raising an exception.
+
+However, there is a problem -- sending events causes unknown code to be
+executed during the transaction commit phase.  There should be a way to
+start a new transaction for event processing after this one is commited.
+
+An `IMailQueueProcessor` or `IDirectMailDelivery` actually delivers the
+messages by using a mailer (`IMailer`) component that encapsulates the
+delivery process.  There currently is only one mailer:
+
+`ISMTPMailer` sends all messages to a relay host using SMTP
+
+If mail delivery succeeds, an `IMailSentEvent` is dispatched by the mailer.
+If mail delivery fails, no exceptions are raised, but an `IMailErrorEvent`
+is dispatched by the mailer.


Property changes on: zope.sendmail/trunk/README.txt
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Name: svn:eol-style
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