BCC in email

### 🔖 Enhancement description

Hi, when sending an email to a topic, all the recipients are visible in the "to:" field. From data security point of view it should be better to add them to BCC so that other recipients not know each others email. Or am I missing a setting?

### 🎤 Pitch

MUST BE

### 👀 Have you spent some time to check if this issue has been raised before?

- [x] I checked and didn't find similar issue

### 🏢 Have you read the Code of Conduct?

- [x] I have read the [Code of Conduct](https://github.com/appwrite/.github/blob/main/CODE_OF_CONDUCT.md)