dovecot - Feb 2023 - Can I encrypt already existant unencrypted mail before I start using the mail-crypt plugin?

Hi,

I am using dovecot 2.3.16, along with postfix and a PostgreSQL database for
managing virtual accounts.

I'd like to start using the mail-crypt plugin. However, I'm having a bit
some difficulty understanding the documentation at

https://doc.dovecot.org/configuration_manual/mail_crypt_plugin 

to reach my goal. I plan to ask questions about those issues by starting new
threads in this mailing list. But before I even come to that, I'd like to
investigate the following:

The above documentation only addresses a clean install and doesn't seem to
mention encrypting already existent unencrypted mails, like my server has. Is it
possible to encrypt those before I start using the mail-crypt plugin, such that
it will be able to decrypt those messages as well?

If it is, I am assuming that how I would go about achieving that will be very
dependent on the ultimate configuration I have in mind (pub/priv keys, etc.). So
I don't expect a full-fledged guide. However, if you could perhaps give a
general overview of what would be needed to achieve this, I would very much
appreciate that.

Thank you.

> On 16/02/2023 07:18 EET mailinglist-subscriptions
<mailinglist-subscriptions at protonmail.com> wrote:
> 
>  
> Hi,
> 
> I am using dovecot 2.3.16, along with postfix and a PostgreSQL database for
managing virtual accounts.
> 
> I'd like to start using the mail-crypt plugin. However, I'm having
a bit some difficulty understanding the documentation at
> 
> https://doc.dovecot.org/configuration_manual/mail_crypt_plugin 
> 
> to reach my goal. I plan to ask questions about those issues by starting
new threads in this mailing list. But before I even come to that, I'd like
to investigate the following:
> 
> The above documentation only addresses a clean install and doesn't seem
to mention encrypting already existent unencrypted mails, like my server has. Is
it possible to encrypt those before I start using the mail-crypt plugin, such
that it will be able to decrypt those messages as well?
> 
> If it is, I am assuming that how I would go about achieving that will be
very dependent on the ultimate configuration I have in mind (pub/priv keys,
etc.). So I don't expect a full-fledged guide. However, if you could perhaps
give a general overview of what would be needed to achieve this, I would very
much appreciate that.
> 
> Thank you.
It will be easiest to do migration to new server, then the data will get
encrypted while migrating. It is possible to write a script to do this, but will
be much more hassle than migration.

You might even be able to do it for one user at a time, by doing migration from
maildir to maildir and then moving the new maildir over the old one.

Aki