Modify stored mail contents?

[Tom Hendrikx]

On 23-07-17 13:07, Evan Martin wrote:
> It looks like the mail filter plugin
> [https://wiki2.dovecot.org/Plugins/MailFilter] is almost exactly what I
> want, except for this:
> 
>> Currently the filtering must not modify the message in any way: mail
> -> write filter -> read filter -> must produce exactly the original mail
> back.
>> (TODO: Modifying the mail during writing would be possible with some
> code changes.)
> 
> Is there any prospect of those code changes being made, so that the
> filter can modify mail contents?
> 
> There's no indication in the docs or the code of what would break if the
> contents were modified, but I'm guessing indexes and caches would be out
> of date and would need to be rebuilt? Is it possible to just disable
> those? I don't need high performance.
> 
> On 22/07/2017 12:51 PM, Evan Martin wrote:
>> Is there a safe way to modify the contents of emails stored by
>> Dovecot? I'll probably only want to change the message bodies, not the
>> headers, if that matters. Looking for ways to do this both for
>> existing emails and new emails as they are received (though anything
>> that works for existing emails can probably just be run again for new
>> emails.) My mail storage is currently mdbox, but I could migrate to
>> another format if that helps.

In general, you should not do this. When a message is stored using IMAP,
it is immutable. The IMAP server also remembers things like size and
assigns messages a unique ID, so mail readers that have already
downloaded the message with that ID, don't have to download the whole
message again to verify whether it's contents have magically changed.
What you're suggesting is not simply compatible with IMAP standards.

The normal way of applying changes to messages is just like a mail
client connecting to IMAP: create a new message and save it to the
store, then delete the old one.

Two people already asked you in this thread what the actual problem is
you're trying to solve, but you failed to answer the question. I'm
afraid that we can't help you any further without more detail.

Kind regards,
	Tom

-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 829 bytes
Desc: OpenPGP digital signature
URL: <http://dovecot.org/pipermail/dovecot/attachments/20170723/0fb6cbf0/attachment.sig>