Rud1ger Sch1erz <nospam_tigre@yahoo.es> writes:

> Hi there,
>
> I wonder, if it's possible to use nnml backend and encrypt every email
> during nnmail-split (one mail - one file).
>
> Or are there any other ideas, to store email encrypted?

If you want to encrypt all the incoming mail, it could be sane to store
your letters on a secure (encrypted) file system. 

If you want to encrypt every mail you get using specifically gnus, you
should find a hook that manipulates letters while getting them.

I suggest that you can take an attention to nnml-prepare-save-mail-hook.
You can find information about it in info [1] documentation.

[1] (info "(gnus)Mail Spool")