Exclude individual e-mails from automatic encryption
In the mailbox web client, you can set up automatic inbox encryption in the settings under Read and write mail | Inbox encryption. Here you can safely paste your public key (in the usual ASCII armor format). If you activate the encrypted mailbox, all incoming mails that are not already recognized as encrypted will automatically be encrypted for you.
After you have activated your encrypted mailbox, it will also be displayed in the filter rules under All settings | Read and write mail | Rules.
If you do not want certain mails to be encrypted, simply create a new filter rule and define sender, subject, or other criteria that the filter can use to identify mails that should not be encrypted. As an action, simply choose keep or let the non-encrypted mails be sorted directly into another folder.
Important: At the bottom, remove the check mark for Check against subsequent rules.
Now place this filter so that it is above the filter “Your encrypted mailbox”. Since filter rules are processed from top to bottom, the first matching filter will be executed – ensuring that your new filter rule is applied before the encryption filter rule.
Of course, you can also create multiple filters in this way to sort out mails that should not be encrypted.