[Dovecot] realtime backup with LDA?

[Steffen Kaiser]

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On Sun, 23 Feb 2014, Francesco wrote:

> i was reading the dovecot-lda documentation as i'm using LDA as a
> delivery agent on my current mailserver configuration.
>
> I was curious to know if there are some options for having a message to
> be delivered to a "twin mailbox" upon delivery.
> this twin mailbox would work as a backup archive for recovering emails
> in case the user accidentally deletes them.
>
> so if i have a user which is alice i would create a second mailbox named
> backup_alice or whatever respecting a predictable schema and then every
> mail delivered to alice would also be delivered to backup_alice.
>
> do you know if this can be done? have any example?

I would add a BCC recipient in the MTA. It's more save in such situation. 
See the thread about qmail and multiple recipients for one mail address.

> i was also planning to use shared folders + ACLS to have backup_alice
> accessible as a read only mailbox directly from the alice imap account.

If posting (appending a new message) would be OK: Add a global Sieve 
script and let each message: fileinto :copy "backup";

Otherwise, use a shell wrapper:

file stdin into temp file,
call Dovecot LDA with original recipient
exit with LDA's exit code on error
call Dovecot LDA with backup recipient
exit 0 # ignores error to prevent repetitive delivery to recipient

I've posted a shell wrapper a few days ago in above mentioned thread.

- -- 
Steffen Kaiser
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