The following terms and concepts are used in this information:
- Backpressure
- CSSMTP stops processing the JES spool file when mail cannot be
sent to the target because the connection to a target server is down
or unresponsive. CSSMTP resumes processing the JES spool file when
a target server connection becomes active.
- Bad spool file
- A bad spool file is a JES spool file that cannot be processed
as the result of security, configuration, syntax, readability, or
delivery issues. The action taken by CSSMTP is subject to the setting
of the BadSpoolDisp statement. For more information about the BadSpoolDisp statement, see z/OS Communications Server: IP Configuration
Reference.
- Checkpointing
- If checkpointing is enabled using the CHKPOINT DD statement in
the CSSMTP started procedure and there are partially processed spool
files on the spool when restarting, CSSMTP attempts to send only the
mail from these spool files that was not previously sent, which reduces
the duplicate mail that is received by recipients. If CSSMTP is started
cold using the -f option, any existing checkpoint
records are flushed before CSSMTP is restarted. For information about
using the CHKPOINT DD statement in the CSSMTP started procedure and about starting CSSMTP with the -f start
option, see z/OS Communications Server: IP Configuration
Reference.
- Dead letter
- A dead letter is created and stored for the following reasons:
- An undeliverable mail notification cannot be returned to the originator
- The original mail message was undeliverable, but did not specify
an originator
- An error report cannot be delivered to the mail administrators
To ensure that dead letters are stored, configure Store on
the DeadLetterAction parameter of the Undeliverable statement. For
information about the Undeliverable statement, see z/OS Communications Server: IP Configuration
Reference.
For examples of customizing the configuration
to handle undeliverable mail, see Customizing the CSSMTP configuration file to handle undeliverable mail.
- ESMTP
- Extended Simple Mail Transfer Protocol
- Extended retry
- If a mail message is not sent to all recipients because the target
servers replied with a retry reply code, another attempt to send the
message is made after the delay that is defined by the RetryLimit
statement. If the long retry limits that are defined by the RetryLimit
statement are exceeded, the mail is placed in the extended retry state.
The mail is saved in a z/OS® UNIX file system directory for extended
retry as defined by the ExtendedRetry statement. If the extended retry
limit is exceeded, the mail is marked as undeliverable. For more information
about mail retry, see Customizing the CSSMTP configuration file to try mail again.
For information about using the RetryLimit
statement and the ExtendedRetry
statement to configure the retry limits, see z/OS Communications Server: IP Configuration
Reference.
- Long retry
- See the definition for extended retry.
- Mail administrator
- The mail administrator is a special user ID for mailing systems,
to which CSSMTP delivers error reports for problems detected while
processing a spool file from the JES spool data set. For information
about using the MailAdministrator statement to configure
up to four mail administrator addresses, see z/OS Communications Server: IP Configuration
Reference.
- Message content
- The headers and the structured body of a mail message. A separate
Multipurpose Internet Mail Extensions (MIME) specification provides
the definitions for structured bodies.
- MTA
- Message transfer agent
- SMTP
- Simple Mail Transfer Protocol
- SMTP command
- A command sent from the client to the SMTP server that lets the
server know what information is being sent. For example, MAIL FROM:
is a command.
- SMTP reply
- The acknowledgement, positive or negative, sent from an SMTP server.
Replies are in US ASCII (ISO8859-1).
- SMTP server
- A network application implementing the SMTP protocol that accepts
mail messages from SMTP clients.
- Target server
- A target server is the resolved or configured IP address from
a TargetServer statement. The first four target servers are used by
CSSMTP. For information about using the TargetServer statement to configure a
target server, see z/OS Communications Server: IP Configuration
Reference.
- Undeliverable mail
- Mail messages that cannot be delivered. CSSMTP processes and tries
to send all mail messages in the spool file. Sometimes, one or more
of these mail messages might be undeliverable. Examples of what causes
undeliverable mail include:
- A problem with the mail message itself, such as the message size
- A problem with the recipient record (RCPT TO:), such as an unknown
mailbox
- A mail message requires a secure connection and none of the target
servers support the STARTTLS SMTP command
- Security problems
- A networking problem, such as being unable to reach a target host
that has the capabilities that are needed for the mail message
For examples of customizing the configuration to handle undeliverable
mail, see Customizing the CSSMTP configuration file to handle undeliverable mail.
- Undeliverable mail notification
- CSSMTP creates an undeliverable mail notification when the ReturntoMailFrom
parameter is set to YES on the Undeliverable statement and the mail
message cannot be delivered. This notification contains the reply
from the target server, describing the reason that the mail message
was undeliverable and the text of the original mail message. If the
undeliverable mail notification cannot be sent immediately, it is
not tried again and is subject to the setting of the DeadLetterAction
parameter of the Undeliverable statement.
For examples of customizing
the configuration to handle undeliverable mail, see Customizing the CSSMTP configuration file to handle undeliverable mail.