What you must never send

Absolute prohibitions

• Passwords, SMS codes, security answers. Not for a "strength check", not for anything.
• Full card numbers, CVV, account details. To analyse spending, amounts and categories are enough.
• Identity documents. Passport, licence, insurance numbers — including photographs.
• Medical documents with identifiers. Test results together with a name and date of birth.
• Other people's personal data. Their messages, contacts, documents — you have no right to dispose of data that isn't yours.
• Trade secrets. Not without a corporate plan and your employer's permission.

The redaction technique

Almost every task keeps working when the real values are replaced with placeholders:

Instead of: "Client Maria Petrova, account 40817…, complains about…"
Send:       "Client A (individual, with us 3 years) complains about…"

The structure of the problem is preserved, the advice is identical, and you substitute the real values into the finished result yourself. The cost is about fifteen seconds.

A special case: screenshots and files

A screenshot captures far more than you intend: background windows, browser tabs, the notification bar, document headers and footers, the neighbouring rows of a spreadsheet. Crop deliberately and look at what's actually in the frame before you upload.

If you've already sent something

Delete the conversation, change any credentials that appeared in it, and — where the service offers it — submit a data deletion request. If it was company data, tell whoever is responsible immediately rather than trying to fix it quietly.

Cheat sheet

• Never: passwords, card details, ID documents, other people's data.
• Redact — the structure is what matters, not the values.
• Check what's in a screenshot before uploading.
• Already sent? Delete, change credentials, report it.