Just after when Sympa's
sympa_msg.pl daemon fetches an incoming
message from the incoming spool (
directory), it executes some sorts of inspection on the message,
and will ignore the message that does not meet certain requirements.
Additionally, list owners may choose customized policies based on authorization scenario so that they can control message acceptance.
Checkpoints built in Sympa
Some of requirements by Sympa are mandatory and the others are optional.
The messages ignored according to any of requirements will be kept in
bad directory in incoming spool and will no longer be processed.
Existence of mandatory header fields
If the message did not have
Messsage-ID:header field, it will be ignored.
If the message did not have available sender address, it will be ignored. The "sender address" is an originator address of the message suggested by message header fields. By default, it is taken from
From:header field (See also "
Some sorts of automated messages may be ignored. This feature is enabled by default (See
If sender address (see above) includes any of well-known mailbox names, it may be ignored (See
If message header contains a field signifying automated message, message will be ignored. In particular,
X400-Conntent-Identifier:(RFC 2156) are supported.
If incoming message has
X-Loop:header field including the same address as target list, the message will be ignored.
On the other hand, Sympa adds
Auto-Submitted:field to the messages generated by mailing list system itself, and adds
X-Loop:header field to the messages delivered by Sympa itself.
If already known message ID was found, the message will be ignored.
sympa_msg.plkeeps message IDs of recently delivererd messages and detects duplication. This feature cannot be disabled.
See also "Loop prevention".
The other criteria
Sympa can ignore message that excceeds specified message size (See "
Optional Antivirus plug-in may ignore the message containing potentially insecure content (See "Antivirus plug-in").
Check by authorization scenario
The list owner can choose
send authorization scenario to control
who can send to the list (See also
"Authorization scenarios" and
This scenario may return one of following results:
Forwarding to moderators. The message will be forwarded to list moderator(s) so that they may re-post it to the list by theirselves.
Holding message for moderation. The message will be held in the moderation spool and wait for moderation by list moderator. Only the messages authorized by moderators will be delivered through the list.
Holding message for confirmation. The message will be held in the authorization spool and wait for confirmation by the sender. Only the messages authorized by sender will step forward to further processing such as delivery.
Denying message. The message will no longer be delivered to list members. Unless "
quiet" modifier is specified, deliovery status notification will be sent back to the sender.