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Subsections

23. Bounce management

Sympa allows bounce (non-delivery report) management. This prevents list owners from receiving each bounce (1 per message sent to a bouncing subscriber) in their own mailbox. Without automatic processing of bounces, list owners either go mad, or just delete them without further attention.

Bounces are received at mylist-owner address (note that the -owner suffix can be customized, see 7.8.4, page [*]), which should be sent to the bouncequeue program via aliases :

	\samplelist-owner: "|/home/sympa/bin/bouncequeue \samplelist"

bouncequeue (see 2.2, page [*]) stores bounces in a /home/sympa/spool/bounce/ spool.

Bounces are then processed by the bounced.pl daemon. This daemon analyses bounces to find out which e-mail addresses are concerned and what kind of error was generated. If bouncing addresses match a subscriber's address, information is stored in the Sympa database (in subscriber_table). Moreover, the most recent bounce itself is archived in bounce_path/mylist/email (where bounce_path is defined in a wwsympa.conf parameter and email is the user e-mail address).

When reviewing a list, bouncing addresses are tagged as bouncing. You may access further information such as dates of first and last bounces, number of received bounces for the address, the last bounce itself.

With these informations, the automatic bounce management is possible:


23.1 VERP

VERP (Variable Envelop Return Path) is used to ease automatic recognition of subscribers email address when receiving a bounce. If VERP is enabled, the subscriber address is encoded in the return path itself so Sympa bounce management processus (bounced) will use the address the bounce was received for to retreive the subscriber email. This is very usefull because sometimes, non delivery report don't contain the initial subscriber email address but an alternative address where messages are forwarded. VERP is the only solution to detect automaticaly these subscriber errors but the cost of VERP is significant, indeed VERP requires to distribute a separate message for each subscriber and break the bulk emailer grouping optimization.

In order to benefit from VERP and keep distribution process fast, Sympa enables VERP only for a share of the list members. If texttt verp_rate (see 7.8.1,page [*]) is 10% then after 10 messages distributed in the list all subscribers have received at least one message where VERP was enabled. Later distribution message enable VERP also for all users where some bounce wer collected and analysed by previous VERP mechanism.


next up previous contents index
Next: 24. Antivirus Up: Sympa Mailing Lists Management Software version Previous: 22. Shared documents   Contents   Index
root 2006-02-28