[Dovecot] manipulating mails

[Steffen Kaiser]

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On Thu, 15 Apr 2010, Sven wrote:

> i want to move mails from some specific imap folder to some other folder on 
> the filesystem to precess them further more.
> but maybe i want to copy the mail and then set the seen flag.
> i think both can be done via imap,
> but maybe i want to add some tag/keyword, text or attachment from some 
> processing skript with processing informations
> thinks getting more complex ...

In IMAP storage messages are immutable, per spec. That means: You cannot 
transparently change the content of a message, e.g. add/remove headers or 
(parts of) the body, once the message has been delivered.

If you do it the IMAP way, each manipulated messages (I mean the content, 
not the keywords/tags/flags) becomes a new message, hence, the clients 
might download it again.

If you keep that in mind, you can successfully manipulate the content of 
messages in Maildir by:

1) rename message somewhere else,
2) manipulate it
3) rename it to maildir_mailbox/tmp
4) adjust access permissions
5) rename it to maildir_mailbox/new or ../cur
making sure the file gets a new filename stem (part of filename before the 
colon) than it had originally.

If a new file pops up in cur/new, Dovecot assumes a non-Dovecot delivery 
and re-indexes the file next time the user accesses the mailbox.

To manipulate the flags I would use PREAUTH.

You can savly remove files from a Maildir.

Regards,

- -- 
Steffen Kaiser
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