Java Doc for MessageProcessor.java in  » Web-Mail » james-2.3.1 » org » apache » james » fetchmail » Java Source Code / Java DocumentationJava Source Code and Java Documentation

Class MessageProcessor handles the delivery of MimeMessages to the James input spool.

Messages written to the input spool always have the following Mail Attributes set:

org.apache.james.fetchmail.taskName (java.lang.String)

The name of the fetch task that processed the message

org.apache.james.fetchmail.folderName (java.lang.String)

The name of the folder from which the message was fetched

Messages written to the input spool have the following Mail Attributes set if the corresponding condition is satisfied:

org.apache.james.fetchmail.isBlacklistedRecipient

The recipient is in the configured blacklist

org.apache.james.fetchmail.isMaxMessageSizeExceeded (java.lang.String)

The message size exceeds the configured limit. An empty message is written to the input spool. The Mail Attribute value is a String representing the size of the original message in bytes.

org.apache.james.fetchmail.isRecipientNotFound

The recipient could not be found. Delivery is to the configured recipient. See the discussion of delivery to a sole intended recipient below.

org.apache.james.fetchmail.isRemoteRecievedHeaderInvalid

The Receieved header at the index specified by parameter remoteReceivedHeaderIndex is invalid.

org.apache.james.fetchmail.isRemoteRecipient

The recipient is on a remote host

org.apache.james.fetchmail.isUserUndefined

The recipient is on a localhost but not defined to James

org.apache.james.fetchmail.isDefaultSenderLocalPart

The local part of the sender address could not be obtained. The default value has been used.

org.apache.james.fetchmail.isDefaultSenderDomainPart

The domain part of the sender address could not be obtained. The default value has been used.

org.apache.james.fetchmail.isDefaultRemoteAddress

The remote address could not be determined. The default value (localhost/127.0.0.1)has been used.

Configuration settings - see org.apache.james.fetchmail.ParsedConfiguration - control the messages that are written to the James input spool, those that are rejected and what happens to messages that are rejected.

Rejection processing is based on the following filters:

RejectRemoteRecipient

Rejects recipients on remote hosts

RejectBlacklistedRecipient

Rejects recipients configured in a blacklist

RejectUserUndefined

Rejects recipients on local hosts who are not defined as James users

RejectRecipientNotFound

See the discussion of delivery to a sole intended recipient below

RejectMaxMessageSizeExceeded

Rejects messages whose size exceeds the configured limit

RejectRemoteReceievedHeaderInvalid

Rejects messages whose Received header is invalid.

Rejection processing is intentionally limited to managing the status of the messages that are rejected on the server from which they were fetched. View it as a simple automation of the manual processing an end-user would perform through a mail client. Messages may be marked as seen or be deleted.

Further processing can be achieved by configuring to disable rejection for one or more filters. This enables Messages that would have been rejected to be written to the James input spool. The conditional Mail Attributes described above identify the filter states. The Matcher/Mailet chain can then be used to perform any further processing required, such as notifying the Postmaster and/or sender, marking the message for error processing, etc.

Note that in the case of a message exceeding the message size limit, the message that is written to the input spool has no content. This enables configuration of a mailet notifying the sender that their mail has not been delivered due to its size while maintaining the purpose of the filter which is to avoid injecting excessively large messages into the input spool.

Delivery is to a sole intended recipient. The recipient is determined in the following manner:

1. If isIgnoreIntendedRecipient(), use the configured recipient
2. If the Envelope contains a for: stanza, use the recipient in the stanza
3. If the Message has a sole intended recipient, use this recipient
4. If not rejectRecipientNotFound(), use the configured recipient

If a recipient cannot be determined after these steps, the message is rejected.

Every delivered message CURRENTLY has an "X-fetched-from" header added containing the name of the fetch task. Its primary uses are to detect bouncing mail and provide backwards compatibility with the fetchPop task that inserted this header to enable injected messages to be detected in the Matcher/Mailet chain. This header is DEPRECATED and WILL BE REMOVED in a future version of fetchmail. Use the Mail Attribute org.apache.james.fetchmail.taskName instead.

MessageProcessor is as agnostic as it can be about the format and contents of the messages it delivers. There are no RFCs that govern its behavior. The most releveant RFCs relate to the exchange of messages between MTA servers, but not POP3 or IMAP servers which are normally end-point servers and not expected to re-inject mail into MTAs. None the less, the intent is to conform to the 'spirit' of the RFCs. MessageProcessor relies on the MTA (James in this implementation) to manage and validate the injected mail just as it would when receiving mail from an upstream MTA.

The only correction applied by MessageProcessor is to correct a missing or partial sender address. If the sender address can not be obtained, the default local part and default domain part is added. If the sender domain part is absent, the default domain part is added.

Mail with corrections applied to the sender address will most likely pass Matcher tests on the sender that they might otherwise fail. The Mail Attributes org.apache.james.fetchmail.isDefaultSenderLocalPart and org.apache.james.fetchmail.isDefaultSenderDomainPart are added to the injected mail to enable such mail to be detected and processed accordingly.

The status of messages on the server from which they were fetched that cannot be injected into the input spool due to non-correctable errors is determined by the undeliverable configuration options.

Method computeRemoteDomain answers a String that is the RFC2822 compliant "Received : from" domain extracted from the message being processed for the remote domain that sent the message.

Often the remote domain is the domain that sent the message to the host of the message store, the second "received" header, which has an index of 1.

Method getSender answers a MailAddress for the sender. When the sender local part and/or domain part can not be obtained from the mail, default values are used.

Handler for when the folder does not support the SEEN flag.

Method computeRemoteDomain answers a String that is the RFC2822 compliant "Received : from" domain extracted from the message being processed for the remote domain that sent the message.

Often the remote domain is the domain that sent the message to the host of the message store, the second "received" header, which has an index of 1. Other times, messages may be received by a edge mail server and relayed internally through one or more internal mail servers prior to arriving at the message store host. In these cases the index is 1 + the number of internal servers through which a mail passes.

The index of the header to use is specified by the configuration parameter RemoteReceivedHeaderIndex. This is set to point to the received header prior to the remote mail server, the one prior to the edge mail server.

"received" headers are searched starting at the specified index. If a domain in the "received" header is not found, successively closer "received" headers are tried. If a domain is not found in this way, the local machine is used as the domain. Finally, if the local domain cannot be determined, the local address 127.0.0.1 is used.

Method createMessage answers a new MimeMessage from the fetched message.

If the maximum message size is exceeded, an empty message is created, else the new message is a copy of the received message.

Method getSender answers a MailAddress for the sender. When the sender local part and/or domain part can not be obtained from the mail, default values are used. The flags 'defaultSenderLocalPart' and 'defaultSenderDomainPart' are set accordingly.

Handler for when the folder does not support the SEEN flag. The default behaviour implemented here is to log a warning and set the flag anyway.

Subclasses may choose to override this and implement their own solutions.