Novell GROUPWISE 8 - POST OFFICE AGENT User manual

Post Office Agent
IX
473
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IX
Post Office Agent
Chapter 35, “Understanding Message Delivery and Storage in the Post Office,” on page 475
Chapter 36, “Configuring the POA,” on page 487
Chapter 37, “Monitoring the POA,” on page 529
Chapter 38, “Optimizing the POA,” on page 561
Chapter 39, “Using POA Startup Switches,” on page 581

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Understanding Message Delivery and Storage in the Post Office
35
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35
Understanding Message Delivery
and Storage in the Post Office
A post office is a collection of user mailboxes and GroupWise®objects. Messages are delivered into
mailboxes by the Post Office Agent (POA). The following topics help you understand the post office
and the functions of the POA:
Section 35.1, “Post Office Representation in ConsoleOne,” on page 475
Section 35.2, “Post Office Directory Structure,” on page 476
Section 35.3, “Information Stored in the Post Office,” on page 476
Section 35.4, “Post Office Access Mode,” on page 480
Section 35.5, “Role of the Post Office Agent,” on page 481
Section 35.6, “Message Flow in the Post Office,” on page 483
Section 35.7, “Cross-Platform Issues in the Post Office,” on page 483
35.1 Post Office Representation in ConsoleOne
In ConsoleOne®, post offices are container objects that contain at least one POA object, as shown
below:
Figure 35-1 ConsoleOne View Showing the POA Object
Although each post office is linked to a domain, it does not display as subordinate to the domain in
the Console View. However, using the GroupWise View, you can display post offices as subordinate
to the domains to which they are linked in your GroupWise system.

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Figure 35-2 GroupWise View Showing Post Offices in Relationship to Domains
35.2 Post Office Directory Structure
Physically, a post office consists of a set of directories that house all the information stored in the
post office. See “Post Office Directory” in GroupWise 8 Troubleshooting 3: Message Flow and
Directory Structure.
35.3 Information Stored in the Post Office
The following types of information are stored in the post office:
Section 35.3.1, “Post Office Database,” on page 476
Section 35.3.2, “Message Store,” on page 476
Section 35.3.3, “Guardian Database,” on page 478
Section 35.3.4, “Agent Input/Output Queues in the Post Office,” on page 478
Section 35.3.5, “Libraries (optional),” on page 479
All databases in the post office should be backed up regularly. How often you back up GroupWise
databases depends on the reliability of your network and hardware. See Section 31.2, “Backing Up a
Post Office,” on page 423.
35.3.1 Post Office Database
The post office database ( wphost.db ) contains all administrative information for the post office,
including a copy of the GroupWise Address Book. This information is necessary for users to send
messages to others in the GroupWise system.
35.3.2 Message Store
GroupWise messages are made up of three parts:
Message Header: The message header contains addressing information including the sender’s
address, recipient’s address, message priority, status level, and a pointer that links the header to
the message body.

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Message Body: The message body contains the message text in an encrypted format and a
distribution list containing user IDs of the sender and recipients.
File Attachments (optional): File attachments can be any type of file that is attached to the
message.
The message store consists of directories and databases that hold messages. The message store is
shared by all members of the post office so only one copy of a message and its attachments is stored
in the post office, no matter how many members of the post office receive the message. This makes
the system more efficient in terms of message processing, speed, and storage space.
All information in the message store is encrypted to prevent unauthorized access.
The message store contains the following components:
“User Databases” on page 477
“Message Databases” on page 477
“Attachments Directory” on page 478
User Databases
Each member of the post office has a personal database (
userxxx.db ) which represents the user’s
mailbox. The user database contains the following:
Message header information
Pointers to messages
Folder assignments
Personal groups
Personal address books
Rules
Contacts
Checklists
Categories
Junk Mail lists
When a member of another post office shares a folder with one or more members of the local post
office, a “prime user” database (
puxxxxx.db ) is created to store the shared information. The “prime
user” is the owner of the shared information.
Local user databases and prime user databases are stored in the
ofuser directory in the post office.
Message Databases
Each member of the post office is arbitrarily assigned to a message database (
msgnnn.db ) where the
body portions of messages are stored. Many users in a post office share a single message database.
There can be as many as 255 message databases (numbered 0 through 254) in a post office. Message
databases are stored in the
ofmsg directory in the post office.
Historical Note: Prior to GroupWise 7, the POA created a maximum of 25 message databases per
post office. The current maximum of 255 message databases speeds up message delivery and
minimizes user impact if a database is damaged.

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Outgoing messages from local senders are stored in the message database assigned to each sender.
Incoming messages from users in other post offices are stored in the message database that
corresponds to the message database assigned to the sender in his or her own post office. In each
case, only one copy of the message is stored in the post office, no matter how many members of the
post office it is addressed to.
Attachments Directory
The attachments directory (
offiles ) contains subdirectories that store file attachments, message
text, and distribution lists that exceed 2 KB. Items of this size are stored more efficiently as files
than as database records. The message database contains a pointer to where each item is found.
35.3.3 Guardian Database
The guardian database ( ngwguard.db ) serves as the master copy of the data dictionary information
for the following subordinate databases in the post office:
User databases ( userxxx.db )
Message databases ( msgnnn.db )
Prime user databases ( puxxxxx.db )
Library databases ( dmsh.db and dmxxnn01-FF.db )
The guardian database is vital to GroupWise functioning. Therefore, the POA has an automated
back-up and roll-forward process to protect it. The POA keeps a known good copy of the guardian
database called
ngwguard.fbk . Whenever it modifies the ngwguard.db file, the POA also records
the transaction in the roll-forward transaction log called
ngwguard.rfl . If the POA detects damage
to the
ngwguard.db file on startup or during a write transaction, it goes back to the ngwguard.fbk
file (the “fall back” copy) and applies the transactions recorded in the
ngwguard.rfl file to create a
new, valid and up-to-date
ngwguard.db .
In addition to the POA back-up and roll-forward process, you should still back up the
ngwguard.db, ngwguard.fbk , and ngwguard.rfl files regularly to protect against media failure.
Without a valid ngwguard.db file, you cannot access your e-mail. With current
ngwguard.fbk and
ngwguard.rfl files, a valid ngwguard.db file can be rebuilt should the need arise.
The ngwguard.dc file is the structural template for building the guardian database and its
subordinate databases. Also called a dictionary file, the
ngwguard.dc file contains schema
information, such as data types and record indexes. If this dictionary file is missing, no additional
databases can be created in the post office.
35.3.4 Agent Input/Output Queues in the Post Office
Each post office contains agent input/output queues where messages are deposited and picked up for
processing by the POA and the MTA. The MTA transfers messages into and out of the post office,
while the POA handles message delivery.
For illustrations of the processes presented below, see “Message Delivery to a Different Post Office”
and “Message Delivery to a Different Domain” in GroupWise 8 Troubleshooting 3: Message Flow
and Directory Structure.

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MTA Output Queue in the Post Office
The MTA output queue in each post office is the post_office\wpcsout directory.
If the MTA has a mapped or UNC link to the post office, the MTA writes user messages directly into
its output queue, which requires write access to the post office. If the MTA has a TCP/IP link to the
post office, the MTA transfers user messages to the POA by way of TCP/IP. The POA then stores the
messages in the MTA output queue on behalf of the MTA, so the MTA does not need write access to
the post office.
The
post_office\wpcsout\ofs subdirectory is where the MTA transfers user messages for
delivery by the POA to users’ mailboxes in the local post office.
The MTA
post_office\wpcsout\ads subdirectory is where the MTA transfers administrative
messages instructing the POA admin thread to update the post office database (
wphost.db ).
POA Input Queue in the Post Office
The POA input queue in each post office is the
post_office\wpcsout directory, which is the same
as the MTA output queue.
The
post_office\wpcsout\ofs subdirectory is where the POA picks up user messages deposited
there by the MTA and updates the local message store, so users receive their messages.
The
post_office\wpcsout\ads subdirectory is where the POA admin thread picks up
administrative messages deposited there by the MTA and updates the post office database
(
wphost.db ).
POA Output Queue in the Post Office
The POA output queue (post_office\wpcsin) is where the POA deposits user messages for the MTA
to transfer to other domains and post offices.
Historical Note: In earlier versions of GroupWise, the GroupWise client wrote user messages to the
POA output queue when using direct access to the post office. In GroupWise 6.xand later, client/
server access to the post office is the preferred method.
MTA Input Queue in the Post Office
The MTA input queue in each post office (
post_office\wpcsin ) is the same as the POA output
queue. The MTA picks up user messages deposited there by the POA and transfers them to other
domains and post offices.
For a mapped or UNC link between the domain and post office, the MTA requires read/write access
rights to its input/output queues in the post office. For a TCP/IP link, no access rights are required
because messages are communicated to the MTA by way of TCP/IP.
35.3.5 Libraries (optional)
A library is a collection of documents and document properties stored in a database system that can
be managed and searched. You do not need to set up libraries unless you are using GroupWise
Document Management Services (DMS). See Part VII, “Libraries and Documents,” on page 305.

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Library Databases
The databases for managing libraries are stored in the gwdms directory and its subdirectories in the
post office.
The
dmsh.db file is a database shared by all libraries in the post office. It contains information about
where each library in the post office is located.
Each library has its own subdirectory in the gwdms directory. In each library directory, the
dmxxnn01-FF.db files contain information specific to that library, such as document properties and
what users have rights to access the library.
Document Storage Areas
The actual documents in a library are not kept in the library databases. They are kept in a document
storage area, which consists of a series of directories for storing document files. Documents are
encrypted and stored in BLOBs (binary large objects) to make document management easier. A
document, its versions, and related objects are stored together in the same BLOB.
A document storage area might be located in the post office directory structure, or in some other
location where more storage space is available. If it is located in the post office, the document
storage area can never be moved. Therefore, storing documents in the post office directory structure
is not usually recommended. If it is stored outside the post office, a document storage area can be
moved when additional disk space is required.
35.4 Post Office Access Mode
The GroupWise 6.xand later Windows client and the GroupWise 6.5 and later Linux/Mac client
both use client/server access mode to the post office. This requires a TCP/IP connection between the
GroupWise clients and the POA in order for users to access their mailboxes. Benefits of client/server
access include:
Load Balancing: The workload is split between the client workstation and the POA on another
server. The POA can perform a processor-intensive request while the client is doing something
else.
Database Integrity: The GroupWise client does not need write access to databases in the post
office. Therefore, client failures cannot damage databases.
Reduced Network Traffic: Requests are processed on the POA server and only the results are
sent back across the network to the client workstation.
Tighter Security: Client users do not need to log in to the server where the post office is
located. This eliminates the need for users to have write access to the post office directory.
Scalability: More concurrent users can be supported in a single post office.
Platform Independence: The GroupWise client on any platform can access the post office by
way of TCP/IP communication with the POA.
Simplified Client Connections: The GroupWise client can communicate with any POA in the
GroupWise system. Any POA can then redirect the client to connect to the correct POA for the
users’ post office.

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Historical Note: In GroupWise 5.x, the GroupWise client allowed the user to enter a path to the post
office directory to facilitate direct access mode. The GroupWise 6.xand later clients no longer offer
the user that option. However, you can force the GroupWise 6.xand later client to use direct access
by starting it with the /ph switch and providing the path to the post office directory.
35.5 Role of the Post Office Agent
The GroupWise Post Office Agent (POA) delivers messages to users’ mailboxes, connects users to
their post offices in client/server access mode, updates post office databases, indexes messages and
documents, and performs other post office-related tasks. You must run at least one POA for each
post office.
The following sections help you understand the various functions of the POA:
Section 35.5.1, “Client/Server Processing,” on page 481
Section 35.5.2, “Message File Processing,” on page 482
Section 35.5.3, “Other POA Functions,” on page 482
35.5.1 Client/Server Processing
Using client/server access mode, the GroupWise client maintains one or more TCP/IP connections
with the POA and does not access the post office directly. Consequently, the performance of the
POA in responding to requests from the GroupWise client directly affects the GroupWise client’s
responsiveness to users. To provide the highest responsiveness to client users, you can configure a
POA just to handle client/server processing. See Section 38.1.3, “Configuring a Dedicated Client/
Server POA,” on page 564.
When using client/server access mode, the GroupWise client can be configured to control how much
time it spends actually connected to the POA.
In Online mode, the client is continuously connected.
In Caching mode, the client connects at regular intervals to check for incoming messages and
also whenever the client user sends a message. Address lookup is performed locally. Caching
mode allows the POA to service a much higher number of users than Online Mode.
In Remote mode, the client connects whenever the client user chooses, such as when using a
brief modem connection to download and upload messages.
NOTE: Remote mode is not currently available in the Linux/Mac client.
For more information about the client modes available with client/server access mode, see:
“Using Caching Mode” and “Using Remote Mode” in the GroupWise 8 Windows Client User
Guide
“Caching Mode” in the GroupWise 8 Linux/Mac Client User Guide
Client/server access mode also allows users to access their GroupWise mailboxes from POP and
IMAP clients, in addition to the GroupWise client. See Section 36.2.3, “Supporting IMAP Clients,”
on page 502.

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In client/server mode, the POA is enabled for secure SSL connections by default. If necessary, you
can configure the POA to force SSL connections with all clients. See Section 36.3.3, “Securing the
Post Office with SSL Connections to the POA,” on page 511.
35.5.2 Message File Processing
Messages from users in other post offices arrive in the local post office in the form of message files
deposited in the POA input queue. See Section 35.3.4, “Agent Input/Output Queues in the Post
Office,” on page 478.
The POA picks up the message files and updates all user and message databases to deliver incoming
messages in the local post office. To provide timely delivery for a large volume of incoming
messages, you can configure a POA just to handle message file processing. See Section 38.2.2,
“Configuring a Dedicated Message File Processing POA,” on page 567.
35.5.3 Other POA Functions
In addition to client/server processing (interacting with client users) and message file processing
(delivering messages), the POA:
Performs indexing tasks for document management. See Section 38.3.1, “Regulating
Indexing,” on page 569.
Performs scheduled maintenance on databases in the post office. See Section 36.4.1,
“Scheduling Database Maintenance,” on page 520.
Monitors and manages disk space usage in the post office. See Section 36.4.2, “Scheduling
Disk Space Management,” on page 523.
Restricts the size of messages that users can send outside the post office. See Section 36.2.7,
“Restricting Message Size between Post Offices,” on page 507.
Primes users’ mailboxes for Caching mode. See Section 36.2.6, “Supporting Forced Mailbox
Caching,” on page 506.
Performs nightly user upkeep so users do not need to wait while the GroupWise client performs
it; also creates a downloadable version of the GroupWise Address Book for Remote and
Caching users. See Section 36.4.3, “Performing Nightly User Upkeep,” on page 526.
Provides LDAP authentication and LDAP server pooling. See Section 36.3.4, “Providing
LDAP Authentication for GroupWise Users,” on page 514.
Prevents unauthorized access to the post office. See Section 36.3.5, “Enabling Intruder
Detection,” on page 519.
Tracks the GroupWise client software in use in the post office. See Section 36.2.5, “Checking
What GroupWise Clients Are in Use,” on page 505.
Automatically detects and repairs invalid information in user databases ( userxxx.db ) and
message databases (
msgnnn.db ) for the local post office by using an efficient multi-threaded
process. See Section 38.4.1, “Adjusting the Number of POA Threads for Database
Maintenance,” on page 575.
Automatically detects and repairs invalid information in the post office database ( wphost.db ).
Automatically detects and repairs damage to the guardian database ( ngwguard.db ) in the post
office.