How to Modify Message and add more Attachments

Hello Everyone,

I am working on a product in which we are planning to store voice messages in Dovecot sent by a user to another user. The message would be stored as an email with .wav attachment. Once the Voice message is received, it may get Transcribed. The message can be further be processed and more information can be added to the message later. The original plan was to Modify the email and add New information as attachments to same message.

As I understood, messages stored in Dovecot are immutable. What is the best option to achieve this functionality?

Thanks, Mrinal